Cross-Chain API

Next Milestone Date
July 25, 2022
Boris PolaniaGanesha Upadhyaya
Live on Testnet
Release Date
2022 Q3

This project will create a CrossChain API MVP that allows:

  • Liquidity Providers (LPs) - that have tokens in Ethereum & BSC to add liquidity in Harmony DEXs using a single API
  • Swappers - to move their tokens from/to Ethereum and BSC using a single API


The expected deliverables are

  • Following 4 APIs:
    • LP-Explore
    • LP-AddLiquidity
    • LP-RemoveLiquidity
    • Swapper-Explore
    • Swapper-Swap
  • A client (web-based) that utilizes the aforementioned crosschain apis to explore and perform crosschain activities like adding/removing liquidity, swapping tokens to/from BSC and Ethereum. Work on this client has already started.


All functionality is being developed in Production mode, where the API takes hashes of signed transactions, and Development mode, where the server is run locally and the API takes the PK.

Step-by-step LP

  • Add Liquidity (Alpha) - Alpha Version: 10/04/2021
  • Remove Liquidity (Alpha) - Alpha Version: 10/04/2021
  • Add Liquidity (Beta) - 10/20/2021
  • Remove Liquidity (Beta) - 10/20/2021

Step-by-step Swapper

  • Bridge Approval and Lock - Production and Development (Beta)
  • Bridge Approval, Deposit and Burn - Production and Development (Beta)
  • DEX - Viper Swap - Production and Development (Beta)
  • AWS Deployment (development) - Beta Version: 10/15/2021
  • DEX - Sushi (Pending) - Beta Version: 10/30/2021
  • DEX - Kanga (Pending) - Beta Version: TBD

End2end LP

  • Integration of Add Liquidity functionality into End2End swapper (Pending)

End2end Swapper

  • Combo API call that bridges assets from ETH BUSD into Harmony BUSD (Harmony Bridged Asset), then swaps Harmony BUSD into bscBUSD (Harmony Bridged Asset) on Viper and finally bridges bscBUSD into BUSD in BSC. (Beta)
  • Combo API call that bridges assets from BUSD in BSC into bscBUSD (Harmony Bridged Asset), then swaps bscBUSD into Harmony BUSD (Harmony Bridged Asset) on Viper and finally bridges Harmony BUSD into ETH BUSD. (Development/Refactoring) - Beta Version: 09/27/2021
  • AWS Deployment (development) - Beta Version: 10/15/2021
  • Integration with Sushi (pending) - Beta Version: 10/30/2021
  • Integration with Kanga (pending) - Beta Version: TBD

Explore APIs

  • Share of Pool Metrics in Viper (Alpha) - Alpha Version: 10/08/2021
  • Gas costs (Alpha) - Alpha Version: 10/08/2021
  • APY (Development) - Alpha Version: 10/22/2021
  • Slippage (Development) - Alpha Version: 10/22/2021
  • Share of Pool Metrics (Beta) - Beta Version: 10/20/2021
  • Has Costs (Beta) - Beta Version: 10/20/2021

Meta transactions

  • General Contract Manager that can aggregate signature of multiple hashes for Bridging (Development) - Alpha Version: 01/11/2021


  • Automated Platform for the aggregation of multiple DEXs (Pending) - Alpha Version: 12/01/2021

Web Client

  • Web Client that implements API functionality - Alpha Version: 12/01/2021
  • Define Web client functionality - Version for open discussion and approval 10/15/2021
  • Enroll Collaborator to develop front-end

Development Updates

Week 10/03 - 10/10

  • Received feedback from beta-testers and suggested changes are being implemented
  • Development of UI testnet started
  • Simple mainnet transactions were successful
  • Containerization is complete

Week 10/18 - 10/25

  • Alpha for UI client is live

  • Debugging for API backend is complete
  • Deployed to AWS in test server

Week 10/26 - 10/31

  • Upgrades in client UX

  • Multiple issues with testnet, they are now fixed and it was migrated to the new endpoint
  • Additional Debugging

Week 11/01 - 11/07

  • The App will be now temporarily named Endless Bridge, repo will be in Github this week. If the name sticks and/or does not is objected by core team or the community, it will stay.
  • Heavy Debugging of Dapp-backend integration
  • AWS deployment delayed until debugging complete
  • Improved UI


Week 11/08 - 11/15

  • beta is live in testnet, more debugging is needed, need to find the right AWS to make it public for testing by the community in testnet
  • Some UI improvements
  • image

  • Mainnet released date tentative for Dec 15

Week 11/08 - 11/15

  • Front-end 98% ready, some integration tasks pending, lots of testing
  • some changes for mainnet are being tested

Weeks 11/16 - Dec 05

  • Dapp is not working consistently in mainnet, we think this is mainly because natural delays and user confusion/mistakes mostly on the DEX, what this is causing is that some transactions are never completed, they will fail in the DEX swap (sometimes because there are no gas fees) or even on the bridging. One common issues is, the user will have wrapped asset in their wallet, so even though the bridge fails because she does not have enough gas in eth, the transaction will proceed to swap and even bridge into BSC. The only solution for this is a bot, fairly similar to the one I am developing for oneAnchor, so I am doing that development now with this in mind, so in the short-term both projects will be the same.
  • Minor UI improvements.
  • Improved Manager Contracts are almost completed, the intention of these is to reduce the amount of metamask calls