Swoop: Ethereum-Harmony Cross-Chain DEX Launch!

A Tech Showcase of a Cross-Chain Decentralized Exchange

Sahil Dewan
Harmony
8 min readOct 31, 2020

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After launching the Horizon bridge to swap assets from Ethereum to Harmony, we are excited to announce that our community has launched a technology demo of a cross-chain DEX — Swoop.

Swoop will enable the community to test out the seamless, high-speed and low-fee user experience while exchanging assets in a non-custodial manner on Harmony.

This first version of Swoop demonstrates the easy migration of foundational decentralized finance infrastructure like Uniswap v2 on Harmony, an EVM compatible chain.

The next version, launching in the coming weeks, will be a fully-cross-chain DEX, relying on the Horizon bridge APIs to power cross-chain liquidity. With these launches, the Harmony community is opening the gates for DeFi developers and partners to fork, build and deploy their own DeFi protocols on Harmony, leveraging the fast and low-cost layer-1 infrastructure.

What can you do with Swoop today?

The community can participate in Swoop by adding liquidity to any of the existing pools, creating any asset-pair pools, or trading assets available on Swoop seamlessly — the user experience of Swoop is consistent with Uniswap. This technology demo will help the community get early feedback from users and developers.

The first step before using Swoop is to ensure that you have used the Horizon bridge to migrate your assets from Ethereum to Harmony. Once you have the wrapped assets on your Harmony wallets, you can start playing around with Swoop.

Users can swap any assets using the ‘Swap’ feature or contribute assets to existing pools via ‘Add Liquidity’

To incentivize the the early users on Swoop, the Pangaea community will be distributing up to 10,000 BUSD as rewards for liquidity providers and traders. The Pangaea community has created three pools to bootstrap activity, ONE-BUSD, LINK-WETH, WBTC-WETH. These three pools will capture the additional rewards mentioned above. In addition to these pools, users can create a new pool for any assets on Harmony. Please review the FAQs for more information about pools and rewards.

This incentives campaign will run for a period of two weeks from launch; with starting block #: 5672429; ending block #: 5914349. Since this is a technology demo, at this time there are no governance tokens attached with Swoop, but the community may retrospectively reward the early adopters with governance incentives in the future iterations.

If you want to try out Swoop, go through the quick FAQs below and jump right in swoop.exchange. Here’s a quick recap by our very own Dir. Schmidt.

The Uniswap v2 migration journey on Harmony

Swoop is a project that was originally conceived during one of Harmony’s hackathons. What was initially considered a simple experiment to port a DEX from Ethereum to Harmony soon turned into a sizable project in its own right — Swoop currently consists of 10 separate implementation repositories.

Throughout Swoop’s lifecycle, the developers tried to stay as close as possible to the original Uniswap V2 code base — both in terms of smart contracts and the UI. The smart contracts are nearly identical to the original Uniswap V2 contracts, with just some minor differences for customizing the LP token names and symbols as well as updating the init code hash for the UniswapV2Pair contract. That’s it.

During the development of Swoop, the Harmony team received feedback about updating the EVM compatibility of the chain — Harmony is now consequently running a much more modern EVM layer.

In terms of the interface/UI, the developers had to spend time rewiring smart contract interactions and changing some interactivity to be compatible with Harmony’s Javascript SDK. Although this took additional effort, it has given us very specific insights on Harmony’s current dApp tooling landscape and what we can improve on our tooling most. As a result, over the next few weeks, we’ll be heads down focussing on:

  • Creating a web3-react library compatible with our own OneWallet as well as MathWallet
  • Implementing a full feature ethers.js wrapper interacting with our own Javascript SDK under the hood
  • Creating a full feature web3.js wrapper on top of our Javascript SDK

The end goal is to create a seamless dApp-porting experience from Ethereum over to Harmony.

Swoop has given us a stark reminder— dApps can be extremely fast on Harmony. And cheap. Our intention with Swoop is to demonstrate what Uniswap can look like when it runs with 5 (and soon 3!) second finality and extremely low fees.

We invite everyone to fork, clone, and create your own version of Swoop. We’ve prepared a detailed guide for how you can deploy your own version of Swoop here.

Start BUIDLing with us!

The Pangaea community will host a video AMA next week, to take developers through a tutorial on deploying Ethereum DeFi protocols on Harmony.

We are really excited for developers to play around with the swoop front-end or checkout the smart contracts. Very soon, developers and DeFi protocols will be able to leverage the Horizon Bridge APIs for adding cross-chain assets to their applications and protocols on Harmony.

With the launch of Horizon, Swoop and related developer tools, Harmony is bootstrapping its cross-chain ecosystem for existing and upcoming DeFi developers and partners. We’re extending an open invitation to come and BUIDL with us.

Swoop FAQs

Shared by the Pangaea community

What is Swoop? How is it different than Uniswap or its clones?

Swoop is a crosschain DEX on Harmony. Swoop-v1 is a clone of Uniswap v2. Later versions of Swoop will have crosschain swap and pool functionality.

Swoop-v1 is a protocol for exchanging HRC-20 tokens on Harmony. It eliminates trusted intermediaries and unnecessary forms of rent extraction, allowing for fast, efficient trading. Swoop prioritizes decentralization, censorship resistance and security. Swoop is open-source under the GPL license.

Swoop-v2 will be a crosschain protocol for exchanging tokens directly between different blockchains, at first Ethereum and Harmony. Swoop-v2 will utilize Horizon-v1 (trusted Ethereum-Harmony bridge) to make crosschain swaps.

How does Swoop work?

Swoop is a constant-product automated market maker protocol. Just like Uniswap, Swoop leverages asset pools on Harmony to enable instant asset exchange.

Is Swoop audited?

Swoop is a technology demo and not officially audited yet. Please use at your own risk. The external audit will be completed in the coming weeks. In case you find any issues or bugs, please report on the Swoop Telegram channel or Github

Which pools are available to join as a LP?

You can add any pools by selecting any two assets on Harmony. During the launch, there will be additional rewards in BUSD for these three pools over a 14-day period:

  1. ONE-BUSD
  2. LINK-wETH
  3. wBTC-wETH

To see all bridged assets and contract addresses on Harmony, go to https://bridge.harmony.one/tokens.

To convert your ETH into wETH or wBTC you can swap on Uniswap and then take the wETH or wBTC to Horizon bridge. To convert your BTC into wBTC you can exchange at one of the partners on https://wbtc.network/dashboard/partners. Alternatively you may be able to swap BTC for wBTC in exchanges, or you may exchange to ETH and follow the above steps for converting ETH into wBTC.

What is the launch incentive campaign?

Launch campaign will last 14-days from the launch. During this period, $10,000 in BUSD will be distributed to early liquidity providers and traders.

Starting block #: 5672429; Ending block #: 5914349

Liquidity provider rewards:

Users will be rewarded for providing liquidity for the first 14 days Swoop is live. In addition to rewards for providing liquidity, there will be a bonus reward based on the number of days that users provide liquidity. Rewards will be calculated on a per block basis, based on the percentage share of the liquidity pool. Note that these rewards are additional to liquidity provider fees. The Swoop team will soon launch a front-end that displays rewards earned by the LPs.

Day 1 will have higher rewards in lieu of early participation. $1,500 worth of rewards will be allocated for the three pools on day 1.

Day 2–14 will have $4,500 in rewards distributed among the three pools.

Additionally, there’s a reward for liquidity providers based on how many days one provides liquidity. There is $1,500 allocated for this purpose. The reward will be calculated at the end of the two weeks when we can calculate how many addresses held LP tokens for how many days. This will allow us to come with the total units. (ie. 100 addresses holding for 14 days is 140 units, 100 addresses holding for 13 days is 130 units, which would make a total of 270 units) $1500 will be divided by the total units and distributed to users based on how many days each held.

You can track liquidity provider rewards for each incentivized pool here:

Trading rewards:

During the campaign period, the Pangaea community will randomly select 10 lucky swap transactions on select days. Owners of the select transactions will be rewarded with $250 in BUSD. Any swap transaction is eligible for this draw, once per address.

Why prices on Swoop may be different than the market?

Prices on Swoop are determined by constant product market maker function. When prices are different, there is an opportunity for arbitrage trades, which in turn will push the prices similar to other exchange venues.

Is there a withdrawal fee?

No withdrawal fee to remove liquidity. Free to come in and leave the pools just as in Uniswap.

Will there be retroactive rewards?

Currently, Swoop has no active liquidity mining program besides the launch incentives program. The governance layer has not yet been built and more information will be shared soon. There may or may not be retroactive rewards for the early users to Swoop, similar to Uniswap allocating tokens to early adopters.

Where can I report any issues related to Swoop?

You can add issues here: https://github.com/harmony-one/swoop-interface/issues

Disclaimer

This project is a tech demo in beta. You understand and expressly accept that the beta version of SWOOP is provided to you at your own risk on an “AS IS” and “UNDER DEVELOPMENT” basis. THE DEVELOPERS OF SWOOP MAKE NO WARRANTY WHATSOEVER WITH RESPECT TO THE BETA DEMO, INCLUDING ANY (A) WARRANTY OF MERCHANTABILITY; (B) WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE; (C) WARRANTY OF TITLE; OR (D) WARRANTY AGAINST INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF A THIRD PARTY; WHETHER ARISING BY LAW, COURSE OF DEALING, COURSE OF PERFORMANCE, USAGE OF TRADE, OR OTHERWISE.

Nationals and residents of the following countries are restricted from participation: Afghanistan, Cuba, Democratic Republic of the Congo, Guinea-Bissau, Iran, Iraq, Lebanon, Libya, Myanmar, North Korea, Somalia, Sudan, Syria, Yemen, Zimbabwe, and the Crimea region of Ukraine.

The Swoop project is operated by Pangaea Community around the globe and Hemenglian Technology outside the United States.

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Sahil Dewan
Harmony

Startup guy. Blockchain entrepreneur. Never shy of dreaming big.