What is Atomic Swap?

Our readers often ask us what exactly is Atomic Swap, and how does it guarantee a secured transaction.

Let us look into the technology in more detail.

In Crypto, the term “Atomic” was adopted from databases, where there is a number of database operations that either occur altogether or do not occur at all (or are brought back to their initial condition, if one of the operations is interrupted, or if something else goes wrong).

These operations are named Atomic Transactions.

Atomicity is one of the four characteristics of “ACID” transactions, with the remaining three being: Consistency; Isolation; Durability. All of these characteristics are necessary, in order to perform a transaction within the database.

The word Swap speaks for itself. It is the exchange of one cryptocurrency for another. By bringing these two meanings together, we get the following definition of an Atomic Swap – a series of operations with two blockchain systems, that lead to a successful exchange of two cryptocurrencies. If one of the conditions of the transaction is not met, the swap is not confirmed, excluding a situation where only one of the two participants receives their cryptocurrency.

The principals of the atomic swap are used in a variety of decentralized exchange technologies. For example, in all sorts for onchain DEXax ( idex, waves, etherdelta, bitshares) and Cross-Chain exchanges (komodo, hodlhodl, swap.online). In the near future we expect to see them be used in PCN (Payment Channel Networks), for instance – Lightning Network.

All of these technologies used differently and have various levels of decentralization. Nevertheless, they all solve the problem of creating a balance between decentralization and speed. The usage of atomic swaps is becoming more popular among Cross Chain exchanges based on HTLC technologies (Hash Time Lock Contract).

As you already know, Hash – is a one-way encryption, with a determined result. This means that for any given secret you will always get the same encrypted line that is difficult to reconstruct (if being precise – very-very hard to reconstruct).

HTLC is a smart contract for an agreed amount of cryptocurrency. The amount can only be sent to a predetermined wallet(address – account) after providing the secret to the hash junction within the given time frame. When creating a contract, you only know the hash function of the secret, keeping the secret itself unavailable to the public. By creating symmetric HTCL on two different block-chains, you get a simplified Atomic Swap mechanism.

Alice creates a smart contract on the Bitcoin blockchain, stating Bob’s address as the beneficiary. Bob creates the same exact contract, but only on the Ethereum blockchain, mentioning Alice’s address as the beneficiary. Both contracts use the same Hash function, but only one of the two parties knows the Hash functions secret.

atomic swap how it works

There is no difference who knows the secret, as long as the party that does know it creates a contract with a more extended time frame.

Here is how the HTLC works. Both of the contracts are symmetric, and the first party to receive their crypto-currency is the one that holds the secret. For example, Alice is the holder of the secret. She provides the Secret to Bob’s smart contract on the Ethereum BlockChain. Once the smart contract receives the secret, it calculates its hash function, and if it matches the hash function in the smart contract, Alice will receive here Ethereum, that will be sent to her wallet.

As we know, all the operations in the blockchain are seen by the public, so when Alice reveals the secret – Bob will immediately receive it. Given that Alice’s Bitcoin Blockchain contract holds the exact same hash function when Bob provides it with the secret he automatically received his Bitcoins to his wallet.

If for some reason Alice does not reveal the secret, Bob will get his Ethereum back after his smart contract’s time frame runs out. In addition, if Alice provides an incorrect secret, the calculation will not match the hash function of Bob’s smart contract, not allowing the transfer of the funds.

atomic swap cryptocurrency

It’s that simple.

You can find more details on HTLC on the internet with different examples of how there are used.

Every Atomic Swap goes through two stages.

The first stage – “Order Matching”. Reaching an agreement between two participants of the Swap. To be precise, this important stage has to be done before the atomic swap. How this stage is accomplished defines projects from one another. There are different “handshake” protocols that can be used, for example, some use centralized services or sidechains, others use decentralized order-books.

Swap.online in its initial protocol version uses ipfs pubsub – a fully decentralized protocol for sending messages. Each order that a Market Maker places is distributed through the message channels that the Market Takers are subscribed to. As if announcing through a loudspeaker they are willing to exchange, for example, 10 of their Bitcoins for 100 of your Ethereums.

The Market Takers will see all the new orders after subscribing to the message channels. In order to view the Market Makers order constantly – he or she should always send out messages about its relevance, meaning the Market Maker should always be online in order to confirm an exchange.

Nevertheless, this does not bring any operational inconvenience. Because in any case for an HTLC protocol exchange you must sign the transactions in real time, and a Market Taker can show an interest to your order at any time.

Once a Market Taker decides to accept one of the orders, he/she sends a message of confirmation, and both parties create an HTLC contract on their blockchains and finalize the exchange as shown in the above-mentioned protocol.

Please see other helpful links below:

Why do I need SWAP tokens?

Atomic Swap for the newbies: Swap.Online Guide

Swap.Online By weekly News Digest #2 (Aug 6 – Aug 27)

Product Development

First of all, read about our game changing  solution on the Atomic Swaps exchange between USDT – the most controversial cryptocurrency with the highest capitalization in the world and different blockchains. If you have basic knowledge of C++ , you can see how we solved the problem of the USDT exchange in 200 lines of code. If you have no such experience, it’s time to know what Tether is, that everybody is talking about, why its exchange is important, and how the world leading development team misled 97% of the USDT holders.

Do not hesitate to read about the results of our developers progress in August. They brilliantly improved the stability and usability of our product, solved some issues with the IPFS, tested and implemented the possibility of sending the links on the given order.

Do not miss the news about the Atomic Swaps with EOS in/at the end of the article

Research and Analysis

Swap.Online conducted a comprehensive research of our competitors. Due to the multi-functional nature of our crypto wallet, for the research we considered not only decentralized exchanges but even some centralized services. Also, we wrote shortly on some projects you definitely should look at in 2019.

By the way, the decentralized peer-to-peer instant cross-chain crypto tokens exchange is the initial idea of Swap.Online. Our CEO Alexander Noxon predicted that in 2019 the amount of trading in decentralized exchanges will surpass that of the centralized ones. We decided to look back on the turbulent history of digital money exchange technologies starting from the non-blockchain era of the mid-2000s

to the Atomic Swap DEXs of nowadays.

Finally, we invite you to the ‘final level’ of decentralization – cross-chain interaction. In our research, we explain why this technology is still missing, where we can find its roots, and which teams are the closest to commercial implementation of this tech. The Polkadot project as the pioneers of many-to-many cross-chain interactions is analyzed with particular attention.

See you in September with the Swap.Online Byweekly News Digest #3,

Swap.Online Team

Swap.Online Essential Links

Website: https://testnet.swap.online
GitHub: https://github.com/swaponline
Email: [email protected]
Telegram: https://t.me/swaponline
Facebook: https://www.facebook.com/Swaponline
Twitter: https://twitter.com/SwapOnlineTeam
Wiki: https://wiki.swap.online/
Bitcointalk: https://bitcointalk.org/index.php?topic=4636633

SWAP Token Review

Basic observations on the SWAP token economy

Disclaimer: This document is for information and illustrative purposes only. It is not, and should not be regarded as “investment advice” or as a “recommendation” regarding a token price, including and not limited on how those terms are used in any applicable law or regulation. SWAP token economics and its features might be subject to change.

atomic swap wallet token


As we have already announced (see p. 10) in the project light paper, the SWAP token will be the core element of Swap.Online project monetization. SWAP is ERC-20 token listed on Swap.Online and can be added to plenty of hot crypto wallets. The total SWAP supply is 21M with neither ICO nor mining procedures planned. We avoided the traditional hype-based model of initial coin offering. The value of the SWAP token will depend on its features and functionality.


For now, we define five main functions of SWAP token.

  1. Premium Trading Options. Swap.Online will provide zero-fee for cross-chain exchanges of BTC, ERC-20, USDT, EOS coins. By the way, the default trades will be available with a ‘starter-pack’ interface and a reduced toolkit. SWAP holder will be able to see the reputation and rating of the counterparties, number of trades, market analytics, and other useful information and insights. SWAP tokens are a must-have for daily-traders and market makers.
  2. Building up Reputation. Atomic swap is all about exchanges built on trust and protecting your funds no matter what the intentions of your counterparty are. But we also understand the importance of the time for a swap and the momentum of opportunity. The time could be lost by a cancelled or intentionally slowed down swap by the counterparty. That’s why we’ve introduced a reputation management system which will be done in a centralized way. If you want your reputation to be scored (e.g: as a market maker), we will require a stake in SWAP tokens.
  3. Safety. Working as a part of a proof-of-stake consensus, SWAP tokens will be used as an additional safety guarantee for its holders. For example, in case of an attack on the Node or an unexpected IPFS-connection failure, a new connection will first be provided to the users with SWAP tokens. By the way, it this particular case, the users can connect to any other server.
  4. Advertising. Swap.Online website, being an attractive platform for crypto-traders, will generate high and quality traffic, thus bringing value to the advertising space on our resource. SWAP tokens will be used as a mean of payment for this advertising space.
  5. Token Integration. Swap.Online is a licensed multi-chain hot wallet that can promptly integrate your Сoin into the balance showing it on our homepage. SWAP tokens will be needed to list new ERC-20 and other types of tokens. Maybe, in the near future, we will also provide the possibility of *TOKEN*<->SWAP trades on Swap.Online platform from the first day of their listing.


Our SWAP tokens will be freely traded via the centralized and decentralized exchanges which support ERC-20 tokens. Note: Swap Online OÜ itself DOES NOT sell SWAP tokens at the moment. By the way, in accordance with our roadmap, a significant stake of SWAP tokens will be spent on the project’s development.

We officially avoid giving any predictions about the price of SWAP. But as a reference, our contributors estimate the price of the SWAP token in approximately 1 USD. Thus, Swap.Online capitalisation based on token supply&price is approximately 21M USD and can be compared to CryptoBridge, Lykke Exchange, SingularX, and Legolas Exchange.

You can also compare Swap.Online with its main competitors (see the table below) considering their capitalization, features, and weaknesses.

Fuel Going to Rocket: August Dev Update, Very Last One Prior to the Mainnet

atomic swap wallet update

IPFS-messaging improvement, no way for the null secret and multiple tabs…Atomic Swaps on EOS?

We would like to share with you our latest updates on the development progress that occured during this hot August. Like our previous development report, this one is dedicated mostly to the issues of stability and usability.


Since instant and reliable cross-chain transactions are one of the market problems we address, the stability of swaps is one of our ‘things’. Thus, we’re working hard to avoid all the malfunctions which can occur within the swap process. For example, we improved the process of IPFS-messaging. In our previous articles, we briefly described the usage of this technology in the Atomic Swaps process. “Now in case of IPFS-connection failure, the users are able to get reconnected very shortly. The system checks the correct IPFS-room and reconnects you automatically; as a result, now the lost progress of swap is not an option’, comments the improvement our lead developer Nikita Dementiev.

Also, the mechanism of swaps now considers whether the messages between a market maker and a market taker are finalized correctly or not. Remember our pesky Alice and Bob. Alice is sending a message to Bob. Now in Swap.Online, Mr. Bob should confirm the receipt of the Alicе’s message for the procedure continuation. If he doesn’t, for the bilateral security of traders, the message is requested one more time.

Moreover, now the Swap.Online IPFS-mechanism avoids the proceeding of null secrets. Finding the fact that some transaction secret is null, the mechanism also removes such transaction.

Finally, we prohibited the Swap.Online launch from the multiple tabs. As the processing machine sees the tab when the swap is launched, the six Swap.Online tabs can mislead the user (but not the Swap.Online). So, this limitation (used e.g. in Telegram Web) is introduced with the purpose to secure the stability of swaps.


As we work with the cryptocurrency remittance, we fully accept our user’s desire to know all the details about their swaps’ proceeding. To grant this request, we presented two visualization options. Firstly, now all the errors (e.g. gas insufficiency) are displayed in the swap monitor screen. You are not only unable to lose your money but even to miss a single thing about its status. Secondly, now the progress of the IPFS-connection loading is shown in the left bottom of the start page. You can trace when the connection will be reached and how many users (‘peers’) are online.

Also, now the user is able to copy the link on a given order to the clipboard and send it to a friend. As Nikita says, ‘In addition, you can see, which orders you have opened via the received links. Now, you can discuss it with your friends or post to social network boasting about your success in crypto trading’

atomic swap wallet

The orders you have received via the copied links are highlighted green

Finally, we implemented constant checking of users’ ETH balance. In case of its insufficiency, the user will be informed before the trade.

Moreover, we fixed some minor bugs, checked the SEO-optimization of our site and made Swap.Online operations much easier for low-performance computers with poor RAM. So our service will really be mass adopted.

And now we are getting closer to the good part.

Our team made a tremendous progress on the EOS implementation in our decentralized multi-chain wallet. Why it matters and how it was done – that deserves another single article. Stay tuned and exchange EOS on BTC and ERC-20 tokens in a decentralized way!

The Bridges That Should Be Built: Cross-chain Overview

cross chain swap

Swap.Online addresses the area of cross-chain technologies and continue the series of articles about the most acute issues of nowadays blockchain sphere. We would like to discuss the future of cross-chain, the thorny path to this level of blockchain interaction, and where we are now on this path.

How They Got There: Two Approaches to The Origin of Cross-Chain

Cross-chain as multi-purpose, decentralized, peer-to-peer, direct informational interaction between different blockchains is a complex phenomenon for both cryptocurrencies and the rest of blockchain implementation spheres. Thus, we can explain the origin of cross-chain in terms of at least two approaches.

In a broad sense, to say, ideologically, it is the expression of Web 3.0. inheriting from Web 1.0 with its author-generated content and from Web 2.0 with CMS, usability, etc. Web 3.0 is widely understood as the decentralized, peer-to-peer web. Real decentralization (both political and architectural, in terms of Vitalik Buterin) can be reached only in case of free interaction between different blockchains. Even single centralized element — proxy-token, main server, website administration, etc., should not be considered suitable for Web 3.0.

In a narrow or, if you will, applied sense, cross-chain is the marker of a new level of anonymous encrypted messages transfer. Let’s take the cryptocurrency exchanges (find more on that in our review). Being descendants of the non-blockchain digital currency exchanges, centralized exchanges allowed the interaction between two different chains, but only serving as the centralized point of exchange which resulted in the bulk of vulnerabilities. First decentralized exchanges either use proxy-token (e.g. Waves and NXT) or are pegged to one type of blockchain (EtherDelta and Stellar DEX). So, the launch of cross-chain exchanges using the Atomic Swap technology, e.g. Altcoin.io or Komodo’s BarterDEX (both of them are now in Beta testnet) is among the most anticipated milestones of the sphere evolution in the year of 2018.

Challenges and Responses

In terms of practice, cross-chain solves at least four problems of the blockchain. Firstly, it’s the scalability of network. We have already reviewed proprietary solutions for Bitcoin and Ethereum networks, but the fact is — every isolated blockchain has its bottlenecks making the transactions slow and high-cost. Secondly, it’s isolability: even with CEXs and proxy-token DEXs, different blockchains are still isolated from each other, so, the system based on ERC-20 token has very poor prospects in interaction with Bitcoin-based system. Thirdly, it’s developability: dApps really anticipate cross-chain technologies to adopt useful and interesting solutions. Finally, it is so called ‘shared security’ problem: two interacting blockchains can be much more secure than each of them individually.

Cross-chain can be applied in the spheres of interaction between digital and traditional economy. IoT, Big Data, ID verification, digital banking, money remittances, civil legal proceedings, insurance, copyright protection, crowdfunding, etc., remain a klondike for cross-chain solutions. For example, through the cross-chain solutions can be built a ‘triangle’ between investors, ICO team, and oracle body with no even slightest possibility for anyone to cheat on the whole system. The triangle of such kind can be formed between the shareholders, real estate developers, and supervisory governmental entity within the framework of mortgaged housing construction. And there are plenty of other examples like that.

Polkadot Project: The Infancy of The Pioneer

Polkadot is one of the most promising cross-chain project. It is being developed since 2017 by Parity Technologies (Great Britain), commissioned by Web3 Foundation (Switzerland). The idea of the project is to develop a protocol integrating different blockchains between each other. Structurally it will consist of ‘Parachains’ — the ordinary blockchains even if with different characteristics, ‘Relay chain’ that coordinates consensus and transaction delivery between chains, and ‘Bridges’ — links to blockchains with their own consensus such as Ethereum.

One doesn’t need to be an expert in blockchain to note that ‘Relay chain’ is a kind of very delicate balance. It is maintained by four types of actors in cooperation: validators, collators, nominators and fishermen.

  • Validators secure the Relay chain by their stakes of product tokens (DOTs, native Polkadot blockchain), validating proofs from collators and participating in consensus with other validators;
  • Nominators secure the Relay chain by selecting good validators and staking DOTs;
  • Collators maintain parachains by collecting parachain transactions from users and producing state transition proofs for validators. They also monitor the network and prove bad behaviour to validators;
  • Fishermen act as a kind of the final security frontier, they monitor the network and prove bad behaviour to validators.

In a word, this is a complicated system sharing PoS- and PoW-principles. This system is governed by sophisticated hierarchy of three types of ‘plebiscite’: council, referenda and public referenda. As a result, bad actors lose their stakes (DOTs) and eventually expelled from the network. Nobody has an option to get control over the full network. More on that here.

But the majority of this is still under development: a project is in its early days. Milestones of the project are called PoC (proof-of-concept), in July, 2018, the PoC-2 was released. What’s ready for today? You can download desktop testnet version of the Polkadot (‘Krumme Lanke’) and launch your own node as ‘parachain’: the list of nodes can be tracked online. Relay chain is close to its final image. It is backed by Parity’s Substrate technology written on Rust, however, the core functionality that comprises the state machine was written in WebAssembly (Wasm). Finally, first transaction of some DOTs between two chains was executed in Polkadot network.

By the way, there are a lot of uncertainties about Polkadot. The mainnet release called Polkadot Genesis is scheduled for the Q3, 2019. Developers say they have no idea how many PoCs will be released on the way to that day. Also, they warn that ‘Polkadot may not be successfully developed or may not function as intended and that the Polkadot genesis block may not be deployed as intended or at all. Finally, the project team is still not sure about the role of DOT holders and this token features. All this may seem like a pure overreaction. Nevertheless, the most professional part of crypto community highly appreciates all Polkadot updates.

Cross-chain for Swap.Online

atomic swap eos

Swap.Online includes plenty of cross-chain implementations. Firstly, basic solution for our wallet is cross-blockchain exchange of crypto. Now, the Atomic Swaps with the BTC, ERC-20, ETH, and EOS are already being executed, operations with USDT are successfully tested, NEM coins are to be added very soon. Cross-chain is also used in Cross Swap technology allowing to send crypto during the operation to different addresses. Finally, In the near term, Swap.Online plans to launch Swap.Button — a many-to-one transactional instrument for the acceptance of crypto investments to the blockchain projects with the cross-chain as the inevitable element.

Don’t forget, there are only five days left to mainnet release of Swap.Online cross-chain wallet.

Stay tuned!

Swap.Online Essential Links

Website: https://testnet.swap.online
GitHub: https://github.com/swaponline
Email: [email protected]
Telegram: https://t.me/swaponline
Facebook: https://www.facebook.com/Swaponline
Twitter: https://twitter.com/SwapOnlineTeam
Wiki: https://wiki.swap.online/
Bitcointalk: https://bitcointalk.org/index.php?topic=4636633

Atomic Swap with Tether (USDT)

On the eve of the release on the mainnet, the team of the cross-chain wallet Swap Online is publishing a research study and the code of the atomic swap using USDT.

atomic swap wallet

USD Tether — the equivalent of the dollar on Omni Layer

The solution described above with the protocol “over” the Bitcoin network gave life to one of the most controversial cryptocurrency projects of the last two years — Tether. Tether (symbol Tether — ₮, ticker — USDT) is a hybrid cryptocurrency with a rate binding to one US dollar. Moreover, according to the assurances of Tether Limited, the issuer of the given tokens, the “binding” is to be understood literally, as each purchased token of USDT corresponds to one US dollar available at the disposal of the company.

If we take the three largest exchanges based on their daily turnover of transactions at the time of writing (Binance, OKEx and HuObi), and then track the five most popular trading pairs for each, we will encounter USDT in 13 out of 15 cases.

USDT — the token with the largest capitalization in the world.

All this generates great community interest in faster, safer and cheaper solutions for exchanging Tether into other currencies. Obviously, such a solution could be atomic swaps, which are instant, decentralized cross-chain exchanges. The Komodo laboratory, the main headliners of this technology, who presented it in the autumn of 2017, reported on the successful exchange of KMD to USDT carried out on the BarterDEX platform, Komodo’s own exchanger.At the same time, according to our data, the developers of Komodo made a swap on the ERC20-a version of Tether, which is only available in 3% of cases. Approximately 60 million USDT from global turnover can thus be exchanged using this method, which, obviously, cannot be considered as a solution to the problem. Striking examples of imperfections of existing solutions can be found even on Etherscan.

This fall, the team of https://swap.online is ready to present an atomic swap with Tether. And here’s how we did it.

How Omni conducts transactions

To carry out the Omni transaction, a user needs to create a regular Bitcoin transaction-transfer of 546 satoshi (minimum) with an additional output storing payload using the OP_RETURN op-code. An example of such a transaction. The payload is a mandatory part of any Omni transaction, as it is a sequence of bytes containing all the necessary information about the transaction.

(example on bitcoinjs.js https://gist.github.com/caffeinum/f64a51ce55d5ac9075bb2f5f2f439c0d )

Let us consider what information is stored in the payload itself

transaction marker — 4 bytes, the mandatory part of any Omni payload is always equal to 0x6f6d6e69 — ASCII code omni. If the first 4 bytes of the sequence are not equal to 0x6f6d6e69, then this sequence is not a payload of Omni.

version — 2 bytes, an analog version of the transaction in Bitcoin. For the described algorithm to work, version 0 is used, or that is the same as 0x0000.

transaction type — 2 bytes, transaction type, for an atomic swap it is sufficient to use only “Simple send” transactions, as simple send is the usual sending of omni currency from its address to the address of the recipient. Simple send corresponds to the transaction type code 0, that is, the next 2 bytes 0x0000. Other possible types of transactions exist in Omni.

token identifier — 4 bytes, identifier of the currency used. For example TetherUS has the identifier 31 or 0x0000001f. All tokens created by the Omni protocol at this time can be seen via the following link.

amount — 8 bytes, for a transaction of type Simple send, this is the amount of the sent currency.

As you can see, payload does not store the addresses of senders and recipients of the transactions, these addresses are determined by the Bitcoin transaction in which the payload output was detected. By scanning inputs, the Omni protocol determines who makes the transfer by finding the output of the corresponding address from among the inputs of the transaction p2pkh.

Thus, for a transfer from Alice to Bob of, for example, 50,000,000 TetherUS, we need to create a Bitcoin transaction where one of the inputs will refer to the p2pkh output corresponding to the Alice address. It is also important that this entry be the first in this transaction (the index of this entry in the received transaction would be is minimal or none at all). One of the outputs of this transaction should be the output of p2pkh to Bob’s address, and another output must have been one of the outputs with the following payload:



Atomic Swap on Omni Layer

Suppose that Alice and Bob are willing to make an inter-blockchain exchange of cryptocurrencies. Alice wants to exchange the units of any Omni currency, for example TetherUS (the given currency has the currency identifier # 31 in the Mainnet, then in the text we will only talk about this currency of the Omni protocol, since it is the most popular at the moment, but the algorithm below will work for any currency of the Omni protocol as well) for b units of a cryptocurrency working on another blockchain. (Omni works on top of the Bitcoin blockchain, of course, according to the algorithm below it is possible to exchange TetherUS for Bitcoins, but due to their work on one and the same blockchain, this exchange can be done in a different, more efficient way).


A — blockchain of Bitcoin.

B — the blockchain of the cryptocurrency for which TetherUS is being exchanged.

a — the sum of TetherUS, which Alice wants to exchange.

b — the sum of the cryptocurrency of the adjoining blockchain B, to which Alice wants to exchange her a TetherUS.

Creating a Transaction

1) Bob generates a random value secret.

2) Bob calculates the secretHash by performing the following operation: secretHash = RIPEMD160 (secret)

3) Bob creates and sends an htlc transaction sealed by secretHash

4) Bob sends Alice a secretHash value, and a hash of the hrlc transaction he created in the previous paragraph in order for Alice to make sure that the correct htlc transaction is actually present in the B blockchain.

5) Alice received from Bob the secretHash and hash of the htlc-transaction Bob created, and is convinced that such a transaction is really present in the B blockchain, and that this is indeed a htlc-transaction sealed by the secretHash value.

6) using the received secretHash, Alice creates the following transaction and translates it into the Bitcoin blockchain:

Let us call such a transaction financing_tx. In fact, it is almost an ordinary Bitcoin htlc transaction that is used in atomic swap with the only difference that in the amount field, 546 satoshi is the minimum number of Bitcoins that can be at the output of the transaction, below this value, Bitcoin counts the transaction as dust and does not conduct it.

7) Alice creates a transaction according to the following scheme:

atomic swap tether usdt

Let us call this transaction redeem_tx. Alice creates such a transaction with two inputs: the first is the input referencing the output of funding_tx, which contains the htlc script. Alice does not sign this script, that is, the SigScript field remains completely empty. The second input is the input referring to any unspent exits of Alice, the main condition is that at this output stage there are enough Bitcoins to pay the transaction fee, and this entry is signed by Alice with her private key with the signature type SIGHASH_ALL (that is, she signs the entire transaction except for SigScript fields on the inputs transaction, which makes this transaction immutable. The outputs of the same transaction are the elementary Simple Send and a TetherUS from Alice to Bob (details of what Simple Send, payload is and how it works can be found in another section).

8) Alice sends Bob the redeem_tx created in the previous paragraph and the one she signed herself.

9) Bob got the redeem_tx sent by Alice, checks it, just looks through the inputs and outputs, making sure that this is really a transaction that Alice should have created using the real algorithm. After that, Bob signs the transaction with his private key and provides the secret value in the SigScript of the corresponding redeem_tx entry.

10) Bob sends the signed redeem_tx transaction to the blockchain, thereby transferring the TetherUS currency from Alice to himself. Note — before carrying out this step, we still need to check that Alice’s address has the necessary amount of TetherUS.

11) Alice looks through blockchain A and gets the value secret and uses it in the B blockchain to transfer the funds using the htlc transaction Bob created in point 3. The exchange ends here.

Stating the obvious: naturally the timelock value used by Bob when creating the htlc-transaction must be significantly longer than the timelock that Alice uses, since her htlc transaction should be spent earlier than the htlc created by Bob. This is necessary so that Bob cannot manage to spend both htlc.


Thus, connecting Omni Layer to Swap Online allows users to cover transactions.

Full research you may find in our Github

C++ source code for creating TX

C++ source code for redeem TX


In next examples:
Alice’s Address – 1QCEnxXU9QAsnqfufArkiuangGNGqdE4in.
Bob’s – 1341545XP8GdCiL96osVr3NefXpHbjzoCs

Alice’s TetherUS balance:


Bob’s Tether balance:


Alice changing 1 TetherUS to 0.001 BTC. For make exhcnage they make this steps:

  1. Bob create SECRET –0x832f296f8f2cff3fe553dee413d8fc84def9102be547bd147c02c36b704ebafb
  2. secretHash=0xbd52a5a7d6d5b8367ddfa8417c271c5639f85322.
  3. Bob create transaction and sent to the blockchain  (funding_tx):


  1. Bob sent secretHash to Alice (via offchain messaging)
  2. Alice created and sent to the blochcain (funding_tx):


  1. Alice created redeem_tx, and signed by SIGHASH_ALL algorhytm:

and send it to the Bob for sign (for example via IPFS). note: one of the outputs no have SigScript.

7. Bob sign this transaction and add secret, then send to the blockchain this transaction (redeem transaction):


This transaction have output with “payload” – this transaction is “Omni” transaction:


  1. Alice can parsesecret from bob’s transaction, then she create and broadcast this transaction:


And take bitcoins:)

Alices TetherUS balance after swap:


Bob’s TetherUS balance after swap:


Swap.Online: cross-chain wallet provides zero-fee exchange between USDT, EOS, BTC, ETH, ERC20. https://swap.online/


About autor: Sergei Moiseev https://github.com/TyHDyK

Lightning Strike

swap tokens online walet

Scalability Is Sending a Message

In November 2015, Bitcoin was worth some $450. The vast majority of nowadays problems related to the world of cryptocurrencies remained either totally unknown and unpredictable or had been a province of few cryptographic geeks. By the way, it was blockchain developer Joseph Poon and Thadeus Dryja, Ph.D. in cryptographic primitives and network security at the University of Virginia who (i) prominently spelled out the main alarming limitations of the Bitcoin network in commercial and technical regards and (ii) suggested the solution for these issues is to be found off-chain and only off-chain.

In fact, they contributed to the discussion that would later be called an ‘ideological battle over Bitcoin’s future’ – the Bitcoin scalability problem debate. While the understanding of both realized and proposed ways of this problem’s solution requires a high-degree knowledge in applied maths and coding, the problem itself can be described in a nutshell.

Initially, one block size in the Bitcoin network is limited to 1 MB. As the quantity and amount of transactions grow, it is not enough anymore. Confirmations time-outs are getting longer, while the transaction fees are getting higher. It results in the loss of commercial attractiveness of Bitcoin solutions since no one prefers to pay more and wait more. The situation has to be resolved as it is about the future of both the applied and theoretical dimensions of blockchain.

Obvious Problems, Controversial Solutions

On the face of it, there are two mainstream ways to solve the Bitcoin scalability problem. Adepts of first way proceed from the understanding that the block size is the only limitation to the transaction throughput. So, they say, this limit is to be increased if not removed once and for all. During the years 2015, 2016 and 2017, a series of solutions of this kind was proposed by the Bitcoin developers community. Among the successful are Bitcoin hard-forks, namely Bitcoin XT, Bitcoin Classic, Bitcoin Unlimited and the most popular and viable, Bitcoin Cash. In accordance with their rules, the block size was expended, at first, to 2 MB. Now, the last Bitcoin Cash core update released on May 15, 2018, allows to enlarge the block size up to 32 MB. This process itself generating controversy and anxiety in the world crypto society was followed by the cascade of partially successful ‘agreements’ (Hong Kong, New York etc.) through which the fractions in Bitcoin community tried to implement a new consensus on mining, thus allowing to enlarge the block size to 2 MB.

The very popular Segregated Witness or SegWit solution is a Bitcoin soft-fork, allowing to increase the block size in another way. It splits the transaction into two segments, removing the unlocking signature (“witness” data) from the original portion and appending it as a separate structure at the end. After that, the block (‘on-chain’) size is increased as  signatures are ‘expelled’ from the blockchain. Since the volume of signatures is some half of the full transaction volume, the limit for the block size with the SegWit is around 1.8 MB. SegWit also addresses the issues with malleability. Signatures are impossible to change after being moved out of the transaction data. Marked as a ‘clever hack’ by the Bitcoin Magazine, the SegWit is now among the most popular Bitcoin scalability solutions. Activated on August 24, 2017, with the Bitcoin block number 481 824, SegWit reached the 10 per cent market penetration in two months. Now every 2 of 5 Bitcoin transactions are handled via SegWit. And that is really a lot.

SegWit Transactions Percentage in the Bitcoin Network. Impressive, isn’t it?

Adherents of the second way suppose that the increase of the volume of the block is only a poor remedy for the Bitcoin network scalability problem. According to them, the pivotal problem is blockchain overload, so, the transactions should be conducted without the use of blockchain as it was generally accepted up to nowadays. They observed that some transactions can be handled ‘above’ the blockchain, or, if you will, on the second layer. So, the proponents of this approach stuck to the ‘Second Layer’ solutions.

Unloading The Blockchain

The Lightning Network ideologists Ј. Poon and T. Dryja asked in their whitepaper: “If a tree falls in the forest and no one is around to hear it, does it make a sound?” They compared the transaction between our familiar Alice and Bob to a tree in the forest. “…if only two participants care about an everyday recurring transaction, it’s not necessary for all other nodes in the Bitcoin network to know about that transaction. It is instead preferable to only have the bare minimum of information on the blockchain”, they declared.

There’s a plenty of Lightning Network schemes in the Internet, I had a hard time finding a clear one for you. Have a look: only two peers know the full information about the transaction with only critical data saved in the blockchain.

To put it at its plainest, in the Lightning Network, if Alice and Bob come to the agreement that the tree fell down at 2:45 PM, it is true without regard to public opinion. Their agreement that before the transaction Alice had 0.5 BTC and Bob had 0.4 ВТС, then after the transaction, Alice owned 0.6 BTC and Bob should content himself with 0.3 BTC, is secured by the hash-time lock contract. This transaction is atomic: it is to be finished only in case of bilateral recognition. Thus, there is no way for fraudulent payments: if the transaction is not broadcast within the timeframe defined in the contract, then it is considered null and void. The channel the transaction is sent through is live only for the time of the swap.

From The Idea to Mainnet: Lightning Solutions Development

Unlike the Rayden second-scale solution for the Ethereum ecosystem, which is solely developed by Brainbot Labs, there is a couple of teams working on Lightning Network in parallel. Moreover, the commercial and non-commercial implementations of Lightning are being developed separately. Non-commercial implementation of Lightning is researched by Digital Currency Initiative of MIT Media Lab (project LIT). Commercial implementations are being developed by Blockstream (project Lightning Charge, see the wide range of specifications proposed by Rusty Russel, one of the most well-known Lightning contributors), Lightning Labs (project lnd) and ACINQ (project Éclair). Now, every abovementioned team presented the beta version for the developers and those who would like to test its features with a dummy amount of coins. The up-to-date condition of the Lightning Network connections worldwide can be found here. At the time of publication, it consists of 2699 nodes and 7403 channels with a total capacity of $0.6M.

Lightning Network Channels Live.

It’s no great deal at the time, but it is increasing day by day.

Why does it matter? There are four main spheres of use the Lightning solutions can be implemented in. Firstly, it is the huge sphere of instant payments. With its prompt speed of operation, Lightning Network can bring the Bitcoin close to the b2c-payments, replacing Visa and MasterCard. Then, it is the trading (or exchange) arbitrage. There is presently an incentive to hold funds on exchanges to be ready for large market moves due to 3-6 block confirmation times. It is possible for the exchange to participate in this network and for clients to move their funds on and off the exchange for orders nearly instantly. Micropayments, e.g. machine-to-machine payments in amount of some Satoshis are also waiting for a solution of that kind. Finally, it can open new levels for applied financial smart contracts and escrow as the third parties are totally expelled from the chain.

Swap.Online x Lightning Network: Long Drive Ahead

Swap.Online, as an OTC crypto marketplace, has a lot of common grounds with Lightning Network solutions. First and foremost, it is due to our special interest in the swaps with Bitcoin. It seems to be really appreciated by the market, since the most popular and advanced modern decentralized exchanges support only ERC-20 tokens. We decided to emphasize the possibility of Bitcoin atomic swaps, since it remains the most popular and attainable cryptocurrency. Then, the Lightning Network focus on the machine-to-machine payments and micropayments in common is coincidental with our b2b-product – Swap Button, the tool for receiving the investments in crypto. Finally, big and experienced traders are obviously interested in high-technology, as instant swaps will eventually switch to the Lightning Network. As a result, we have a strong interest in the research of Lightning algorithms.

Swap.Online Essential Links

Website: https://testnet.swap.online
GitHub: https://github.com/swaponline
Email: [email protected]
Telegram: https://t.me/swaponline
Facebook: https://www.facebook.com/Swaponline
Twitter: https://twitter.com/SwapOnlineTeam
Wiki: https://wiki.swap.online/
Bitcointalk: https://bitcointalk.org/index.php?topic=4636633


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Interview with the CEO of Swap.Online Alexander Noxon

Please introduce yourself.

Sasha Noxon, programmer, website developer.

What determined your personal development as a programmer and developer?

The market as such. From the age of 16, I accepted orders on Freelance.ru. I was engaged in everything that brought money. I will not be revealing a secret when I say that mostly it was business websites and online stores.

What projects can you be proud of from those days?

First of all, the website https://pozvonim.com — a feedback widget for sites. In second place, perhaps, the copywriting exchange noxon-text. It no longer functions now.

You said “programmer”. And you can call yourself an entrepreneur?

Of course, I am an entrepreneur. In this regard, I was interested in the blog Spryt.ru back in the day. It was run by a schoolboy earning from advertising on his websites. At the same time, for me there is no division, or an evolution of some kind. I was the creator of websites, worked for a guy, then grew up and became an entrepreneur. No, at different periods of my life I could earn more both from my own projects, and from work for others. I do not think that this is a linear process.

The most predictable question. How did you get to blockchain? What about it attracted you?

It began with an interest in Bitcoin in 2012. As trivial as it sounds, I was attracted to the idea of ​​a free internet currency. Free in terms of emissions, in terms of movement. This is not something that Russia or the US can block. This is more understandable money for me.

So you’re cryptoanarchist?

By no means. I respect cryptoanarchists, I’m interested in them, they are cheerful dudes. But I never considered myself as one of them. Anarchy is not the final state of affairs that the world of cryptocurrencies strives to. On the contrary, anarchy is inadmissible in it.

In which projects you have worked?

Until 2016, I was rather an explorer, not a practitioner. You can learn more about this in my Github. Mostly, I investigated the practical application of smart contracts, IPFS technologies, the properties of ERC-20 tokens. Since 2017, I have headed DAO Casino as a technical director.

“I am not expecting any owners of oil companies”

You saw a huge number of block projects. What good and bad tendencies of 2018 can you name?

It is best to start with the good, isn’t it? (laughs) People had just started understanding cryptocurrencies — what is good and what is bad. They started believing less, and thinking more. Even more important is that the exchanges are now releasing their own tokens, and this leads the macroeconomics of cryptocurrencies to a new level. The model works worse when someone is sitting on commissions from exchange platforms, which they once created. The profitability of the product tokens, in particular the crypto exchanges, depends on the quality of their work, and this is much more important for the community as a whole. Finally, it’s very cool that people are starting to pay attention to cross-chain projects (like Lightning network).

But even unpleasant things are still common. First of all, this is the inertia of investors who cannot affect the teams that they have entrusted their money to. It’s no secret that before the advent of the ICO, the motivation of the team is very high, but new motivation is needed after a successful crowdfunding campaign. In this regard, a large influx of Ether into the industry has served it poorly, as some have been spoiled, others have been deceived. Maybe this is why really big investors are not yet in a hurry to enter this sector…

Another trend! And who is a big investor for you? Where did he get the money?

Investors in this case, above all, are people who have made money on the 2013 and 2017 cryptocurrency boom. It is them first and foremost. The rate of Ether has grown, and they have a lot of money, that’s all.

And, for example, old fat cats, owners of oil companies and others? If you say “big investors are in no hurry” when should we be waiting them?

Look, I do not even think about it. You do not need to think about it. It’s unproductive to wait for these people. The worst thing is that even worthy products from strong teams are now finding it harder to raise the money necessary.

I will tell you another trend, it is neither good nor bad. Now there are a lot of funny ICOs, where people work “as fans”. They just like the idea, it cheers them up, and they invest money in it. These people do not hope for a large income in the foreseeable future from their purchased tokens. It’s something like donating money in games.

So you say “worthy project”, “cool project”? And which projects are the best?

All off-chain and cross-chain ones, especially those that work directly with Bitcoin, which for me remains number 1. Well, and decentralized exchanges with their coins. The future belongs to them, I will not tire of repeating it.

Are there bad projects?

There are no such projects. I will not be hating any projects. Whoever gets the money is good, and they are awaited on the market. And it is good as long as they get the money. Nothing new compared to the “old” economy.

“It is always difficult with strong people”

You directed many projects. Who are you recruiting?

This is very difficult! (laughs). Always in different ways, depends on the task.

No, we need an answer to this question. Let us take another avenue of approach. What is the main principle of your relationship with the team?

Our principles of interaction and payment are published on the site, they can be found. The policy of payment necessarily implies the payment of a part of the work with the tokens of the project.

Payment request form on the site. Any employee receives part of the earnings in SWAP tokens.

I am an adherent of a cautious approach to the freedom of the employee and his schedule. While a person works well, while he has a lot of responsibilities, and he does not fail us, then I’m ready to give him the opportunity to work where he wants and as much as he wants. As the scope of responsibility decreases, the tasks become more specific, a person should go to the office, work on site so that I and others see him.

With strong people it’s always difficult. Strong people are hard to force to work for a common cause. You cannot force a strong programmer to do what you need, but it’s not interesting to him. Of course, a lot can be achieved with money, many are motivated by it, but in the case of really strong people, we are talking about absolutely non-market amounts.

If I pay a lot, then the person works well, and he is interesting to me, and I’m interested in him. It’s the other way around if I pay little.

Are there any categories of people you will not work with or will you quickly fire?

There are. The most dangerous people, whom I will never tolerate, are those who do not adequately assess their competence in different areas of the case, and seek to tell others how to work correctly. You have not done any of “your” tasks, but you are already advising one guy, giving orders to the second one, and criticizing a third! Such people, fortunately, are becoming a rarity, but they are very toxic to the team. As for everything else, everything is trite — I do not like lazy people, who must be constantly kicked, dreamers, projectors, etc. I do not believe in evolution here, by and large. If a person is not a professional, you will not be able to turn him into a professional, or even an average performer.

Swap.Online is the only way”

How and when did the idea of ​​Swap.Online appear? Probably, you will not even be bale to mention an exact date…

On the contrary (opens the computer). On November 22, 2017, in Facebook, I laid out the design of how to exchange a token for Bitcoin. Then I described this as a possible solution for exchanging fiat money and Bitcoin for the tokens of decentralized applications. I made my post in one of the Telegram chats for enthusiasts of the Ethereum blockchain. After some time, an investor wrote to me and said that he saw this text, and some of my smart contracts, and that he liked these ideas. Within a few months, we agreed on the terms, signed the agreement and I left the previous team.

Are not you afraid that by spreading these thoughts in FB that the idea of ​​the project will be simply stolen by someone who is cunning and technically savvy?

No. Open Source in this case is the same as publishing the idea of the likes of ​​”I’m building a house, it has walls and a roof, as well as five floors and an entrance.” Nothing more. The implementation has nothing to do with this, and it will never suffer.

Well, at that time, in terms of implementation, were there some alternatives besides Swap.Online?

No. It was the only way.

But, after all, everyone was fine with centralized exchanges for some time? When did you realize that the time for decentralization has come?

You know, they are satisfied with almost everything nowadays. DEX is the technology of tomorrow, if not the day after tomorrow.

The time has come for some bold predictions from Alexander Noxon. When will the turnover of decentralized exchangers exceed the turnover of centralized ones?

In 2019.

Very soon! What problems of centralized exchanges your Swap.Online will resolve?

best atomic swap wallet

First, it is the freezing of funds in the KYC / AML policy types. On many sites of this kind, for example, on the Korean exchange Bithumb, you can have as much funds as possible, and you will be asked for many documents that you cannot always provide when you decide to withdraw them. When you enter the money, you do not know whether they will give it to you the next time.

Secondly, this is the rate of exchange. The hour is nigh when no one will want to wait for 10 to15 minutes to exchange the Ether to Bitcoin. One or two minutes is what we offer our users.

Thirdly, this is reliability. We do not keep your money, we cannot break something and steal it. There are other risks, they are being worked on, for example, the risk of domain locking, in this case, the affected users may suffer, but we will necessarily make isolated desktop applications.

The cherry on the cake is the rate of our transaction commission. It is zero percent. It’s very easy to remember. Mining fees are 20 cents.

Impressive. Who is your target audience?

Well, first of all, the “hodlers”. These are participants of the cryptocurrency market, who tend to hold their assets for a long time without participating in short-term exchange trading. As a rule, they have a lot of cryptos and they are afraid to transfer them on the classic centralized exchanges. I outlined the reasons above.

In addition, highly-informed people, like blockchain geeks, they will come to us. They are interested in the technological side of the exchange and they tend to use the advanced technologies that we will offer.

And who will surprise you if they come to Swap.Online? Who is the “no-purpose” audience?

Interesting, I have not thought about it. Probably, corporate financial clients. Here, “Alfa-Bank”, for example, will surprise me if they come asking for advertising.

Now three short questions about your project. What is its weakest side?

We are young. Unavoidable explosive growth can demotivate the team. But I already faced this in 2013 and 2017, and I derived an important rule from those events, and that is that you need to have global goals and never stop even if everything is very straightforward.

Does it have a scalability limit, ultimate throughput, or something like that?

There is nothing like that.

In a nutshell, turn to the people who are visiting Swap.Online for the first time.

Leave me your mail: it will be interesting.

“I will play Civilization V”

Let’s talk about the future in the end. Can blockchain change the world, and if so, in which direction?

Yes and no. On the one hand, it’s very good that many people have become interested in Bitcoin in 2017, generated wallets, bought coins. Their life will become more prosperous, reasonable and interesting, and this is very cool. On the other hand, some of the fundamental problems of planet Earth cannot be solved by blockchain technologies.

Be Isaac Asimov. Now there is blockchain, tomorrow there is cross-chain and off-chain. And then what? What’s next?

I think at some point quantum computers, fourth-dimensional technology, time warping, all of them will be involved in this. It is very difficult to describe this now. Probably, everything will begin with quantum computers.

The last question for today. The day has come when you are tired of cryptocurrency and blockchain. What will you do on that day?

The answer is simple: computer games.

Games? Write them? Play them?

Write them.

Favorite game?

“Civilization V”.

Interview with the CEO of Swap.Online

Alexander Noxon

“The world of the cryptocurrencies will not allow anarchy to dominate”

We hope you liked it!

Swap.Online Essential Links

Website: https://testnet.swap.online
GitHub: https://github.com/swaponline
Email: [email protected]
Telegram: https://t.me/swaponline
Facebook: https://www.facebook.com/Swaponline
Twitter: https://twitter.com/SwapOnlineTeam
Wiki: https://wiki.swap.online/
Bitcointalk: https://bitcointalk.org/index.php?topic=4636633

Atomic Swap for the Newbies: Swap.Online Guidе

Atomic Swaps: What’s That Like

atomic swap bitcoin

To start with, Atomic Swap is a technology of direct trade between two different cryptocurrencies with no third parties, middlemen, intermediary tokens etc. Alice sends Bitcoins to Bob, Bob sends Litecoins to Alice. That’s it. The story is about Alice and Bob’s wallets containing cryptos, their decision to exchange, and their computers connected to their respective blockchains.

If Alice owned 5 Bitcoins, but instead wanted 100 Litecoins, and Bob owned 100 Litecoins, but instead wanted 5 Bitcoins, then Bob and Alice could make a trade. To avoid Alice’s possible cheating in accepting Bob’s 100 Litecoins, but then failing to send her 5 Bitcoins, atomic swaps utilizes what is known as hash time-locked contracts (HTLCs).

Hash time-locked contracts ensure that the atomic swap process is completely trustless by ensuring both parties fulfill the requirements of the trade. If this proof is not received within 24 hours (the timeframe depends on various factors), the money is returned to their respective owners.

That’s why this technology matters, as the trade is cancelled if only one of the two parties is unsatisfied.

Therefore, for a trade between Alice and Bob to take place, both must submit their transactions to their respective blockchains, Alice on the Bitcoin blockchain, and Bob on the Litecoin blockchain. In order for Alice to claim the 100 Litecoins sent from Bob, she must produce a number that only she knows, which is used to generate a cryptographic hash (a very long row of letters and numbers), thus providing proof of payment.

Brief History of Atomic Swaps

The idea of fully decentralized transactions comes from the very first papers written by Satoshi Nakamoto about Bitcoin (2008), and even by Nick Szabo about smart-contracts. HLTCs are a particular case (middle 1990s). The Komodo Platform, a fork of the Bitcoin team, was the pioneer of Atomic Swaps. The original idea for atomic swaps was described on the BitcoinTalk forum by forum member Tier Nolan in 2013. Komodo’s lead developer, JL777, recognized the value of the idea, built the necessary framework, and completed his first atomic swap just a year later in 2014. Since then, his team has continued to make tremendous advances in the technology.

On September 19, 2017, they executed the first Atomic Swap between two blockchains, Litecoin and Decred.

Three days later, the first Atomic Swap between the two oldest currencies, Bitcoin and Litecoin, was successfully carried out.

Cross-chain Atomic Swaps technology is now widespread on different blockchains.

Atomic Swaps: Present and Future Application

Currently, this technology is being used for sending money from one blockchain to another. For example, in Swap.Online, we use it for BTC ⇔ ETH and ERC-20 ⇔ BTC swaps. Everyone can change their cryptos in a safe and decentralized manner. You can try it yourself: just follow the instruction manual!

Research on the future of this technology is being carried out in two directions. Firstly, there are a couple of emerging solutions for executing swaps above the blockchain (second-layer scalability) e.g. Lightning Network for Bitcoin, Raiden Network, and Liquidity Network for Ethereum. They are trying to somehow solve the problem of blockchain overloads. Secondly, many researchers are trying to find commercial applications for Atomic Swaps. It is highly likely that they will be used in statistics, banking, logistics, state registers and other areas.

What can we derive from this article? The technology of Atomic Swaps is a way to transfer cryptos from one blockchain to another with the use of special smart contracts set for a limited amount of time. The technology is used for decentralized peer-to-peer cryptocurrency trading.

Your Guide in the World of Cryptos,

Swap.Online team

Swap.Online Essential Links

Medium: https://medium.com/swaponline
GitHub: https://github.com/swaponline
Email: [email protected]
Telegram: https://t.me/swaponline
Facebook: https://www.facebook.com/Swaponline
Twitter: https://twitter.com/SwapOnlineTeam
Wiki: https://wiki.swap.online/
Bitcointalk: https://bitcointalk.org/index.php?topic=4636633