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Interoperability & Bridges

Contracts — hop-protocol

Contracts — hop-protocol is the public repository of Hop Protocol v1 smart contracts powering Hop Exchange. The contracts implement a rollup-to-rollup token bridge that uses intermediary bridge tokens and automated market makers to exchange them for canonical tokens on rollups.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Contracts — hop-protocol — OpenViST project profile in Interoperability & Bridges.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use the repository when you need to inspect or build around Hop Protocol v1 bridge mechanics, especially L1/L2 contract roles, hToken flows, bonder accounting, or transfer-root events.

Who it is for

  • Developers studying rollup bridge contract architecture and transfer lifecycles.
  • Engineers exploring integrations, monitoring, or application interfaces around bridge transfers and AMM swaps.
  • Protocol operators and researchers examining bonder accounting, transfer-root settlement, and challenges.

Documented uses

  • Inspect how L1 and L2 bridge contracts handle token transfers and withdrawals.
  • Understand how hTokens represent underlying tokens and move between rollups.
  • Trace bonder staking, credits, debits, transfer-root bonding, and settlement.
  • Review documented transfer-root challenges and relevant contract event signatures.
Before you choose

Requirements & limits

The repository is public and accessible on GitHub.

  • The protocol design uses bridge tokens as intermediary assets and AMMs to exchange them for canonical tokens on each rollup.
  • L1 and L2 contracts have distinct documented responsibilities, with separate L2 implementations listed for Arbitrum, Optimism, and xDai.
  • When the bonder is offline, receiving-chain withdrawal may wait for the sending chain to relay the transfer to L1.
  • The README includes setup snippets and event signatures, but does not provide a complete environment-specific deployment procedure.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Prepare the documented L1 and L2 contract setup

Follow the repository’s listed dependency and setup stages for L1 and L2 contracts.

Before you start

  • The public hop-protocol/contracts repository
  • An npm-capable development environment

Steps

  1. For L1 setup, remove node_modules/@openzeppelin, cache and artifacts, then run npm i.

  2. Run npm run deploy for the L1 setup.

  3. For L2 setup, run npm run patch-oz.

  4. Run npm run deploy for the L2 setup.

Expected outcome

The documented L1 and L2 setup commands have been followed.

Guide limitations

  • These commands describe setup stages and do not establish that deployment will succeed in a particular environment.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
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Sources checked
16 October 2026
Original website title
hop-protocol/contracts · Official homepage title · retained in its source language
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