Datachain - Harmony<>Cosmos Bridge

Name of Project

Harmony<>Cosmos Bridge by Datachain

Proposal overview

*We re-post this proposal with a few modification due to a procedure matter. You can find an original proposal here.

Datachain is focusing on interoperability solutions for heterogeneous blockchains which are not only public chains but also enterprise chains like Hyperledger Fabric, Corda and Hyperledger Besu. And our solution is compliant to IBC designed by Cosmos and won a grant from ICF for IBC-solidity, which is IBC implementation in Solidity. Thus we will be able to support to build Cosmos<>Harmony Bridge with our abundant experience.

This project is developing a bridge between Harmony and Tendermint based ledgers using the IBC. This bridge will be deployed on the private testnet for each of them.

As a sample application of the IBC, we will develop token transfer using ICS-20. The token on Harmony is assumed to be HRC-20 which will be handled as ICS-20 on Tendermint based ledgers.

Requests from the Datachain team

・The relayer will be implemented based on the YUI-relayer which is in Golang

・Harmony Light Client will be written in Golang

・We will use end to end test to confirm that token transfer can be done based on CLI without Web Frontend implementation

Proposal ask

  • $88,000 for 4months
    • $30,000 : Before developing the Harmony Light Client
    • $58,000 : After developing the Harmony Light Client

Metrics for success

  • Developing Harmony Light Client(HLC) as a Cosmos module in Golang for Tendermint based ledgers like Gaiad.
 specification outline of HLC
   - Use StateProof instead of ReceiptProof
  - Regarding verification, Use Shard Committee(validator set) instead of Checkpoint
  - By taking the above approach we can avoid using an immature MMR.
  • Developing Tendermint Light Client on Harmony
    • *1 We would like Harmony to consider supporting EIP-665
    • *2 Our schedule is estimated with the *2 condition (Other ways may affect the schedule)
  • Developing the relayer in Golang
  • Developing the token transfer sample application which can be executed based on CLI.

Thank you for submitting a proposal to Harmony’s $300M Ecosystem Fund. Allow me to be your representative on behalf of the Grants committee. We are in the process of reviewing your proposal.

If you have more details to add, please do so by replying to this thread. We would also love :blue_heart: to have the Harmony community participate to ask questions and provide feedbacks.

Replaces prior proposal – Harmony<>Cosmos Bridge

@Daiki how does this compare with Stargate?

@Jacksteroo Thanks for asking. Does Stargate mean by this If so, the IBC enabled by Stargate is a bridge for Tendermint based blockchains, which means zone<>zone in the Cosmos ecosystem. What we will be developing is the IBC for heterogenous blockchains, especially Harmony <> Cosmos at this time. This is the big difference. Please let me know, if you have any questions.

@Daiki could you please provide milestones and clearly mark them as completed/in-progress so that we can facilitate partial payments to accommodate the completed work. thanks.

@ganesha here is a current progress and next milestones. Please check it out and feel free to ask me anything.

For $30K : Current progress

  • Tendermint Client on Solidity: 50% (In-progress)
  • Relayer for Harmony :50% (In-progress)
  • Relayer for gaiad: 100% (Completed)
  • E2E env.: 80%(In-progress)

For $58K: Next milestones

  • Tendermint Client on Solidity: Other 50%
  • Relayer for Harmony :Other 50%
  • E2E env.: Other 20%
  • ICS-20 on Solidity
  • Harmony Light Client

The light client has great potential to build out the HLC in other chains, fulfilling the vision of Harmony as the bridge across all chains.

Approved for a Partnership for up to $100K. Looking forward to working with the team to grow the Harmony Ecosystem! :tada:

Meanwhile, to prepare receiving funds, email your identification documents to and create a Gnosis Safe MultiSig wallet at and using instructions below
:arrow_right: Setup Gnosis Safe with MetaMask & 1Wallet

Checkout the Funding FAQ for further info at Harmony Funding FAQ

We’d love :blue_heart: to see weekly updates on this channel to keep the community posted on this proposal’s progress!


Great proposal! Excited to see the milestones completed!

Thanks a lot! Let’s do it :+1:

Notification of all milestones completion!


Phase2:After developing the Harmony Light Client
Idx.0 Tendermint Client on Solidity: 100%
Idx.1 ICS-20 on Solidity:100%
Idx.2 Relayer for Harmony :100%
Idx.3 Relayer for gaiad: 100%
Idx.4 Harmony Light Client : 100%
Idx.5 App using ICS-20:100%
Idx.6 E2E env.:100%

  • Status:Done

  • source code w/Demo scripts (git is here):

  • Harmony Light Client is here

% Payment:57%($58k)

below is attached for reference of payment.
Phase1 :Before developing the Harmony Light Client

Total:43% Idx.0 Tendermint Client on Solidity: 50% Idx.1 ICS-20 on Solidity:0% Idx.2 Relayer for Harmony :50% Idx.3 Relayer for gaiad: 100% Idx.4 Harmony Light Client : 20% (only research and ideation) Idx.5 App using ICS-20:0% Idx.6 E2E env.:80%

  • Status: Done
  • % Payment:43% ($30k)

the original proposal is here as a premise, and we need to confirm assumptions of the original one.


Does it mean the Datachain - Harmony <> Cosmos bridge is ready to use? or ready to be deployed?

We cannot call it ready yet but this achievement is a stepping stone to the next phase of the project with improvements. This Grant not only includes the ibc sample application, but also includes the Harmony Light Client(HLC). We have proposed the HLC specification to the Harmony team, and have confirmed that it works locally. It is described in Assumption 1 in the Original proposal. Thank you.

Hi @Jacksteroo @ganesha, as @Kogaichi reported a week ago, we got our milestone completed. Please let me know exact review and funding timeline and the process.

We understand current Harmony’s situation, however this unclear situation makes us anxious. Thus we would like to know the timeline that you have in mind first. And if you need our support or info, feel free to let us know, we will make every effort.

We hope a whole funding process will complete soon and look forward to your reply.

I have reviewed the grant deliverables:


Thanks a lot for your cooperation in such a difficult situation. From now, we would like to discuss our next milestone. One of the candidate would be leveraging LCP led by us to build Ethereum or Cosmos <> Harmony Bridge or re-launch Horizon.

LCP is a proxy light client verification to realize trust-minimized and gas-efficient cross-chain bridge. And it’s currently supporting IBC as messaging layer, so any cross-chain Dapps can be built on it. But I guess you have been considering next milestone regarding bridge matters, especially Ethereum<>Harmony. We’re grateful if you could let us know about it.


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ohhhhhhhhh I likey… :slight_smile:

yes, the LCP implementation for harmony light client will be very useful to connect not only ethereum and cosmos, but all other chains. i will be supportive of this proposal. could you make a proposal for the same? we can discuss the details in that proposal and community can also chime in with inputs.

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Happy to hear that^^ Would using LCP for Horizon to re-launch be one of your option? Of course we will be launching for all of the major chains in near future and this decision is up to community. But I would like to ask you about this as reference.

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yes, it is an option that we would consider based on your progress and timeline for resuming the bridge. since, it will be a replicable technology for connecting many chains, this contribution will be very valuable.