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Optimism is Ethereum, scaled.

Table of Contents

What is Optimism?

Optimism is a project dedicated to scaling Ethereum's technology and expanding its ability to coordinate people from across the world to build effective decentralized economies and governance systems. The Optimism Collective builds open-source software for running L2 blockchains and aims to address key governance and economic challenges in the wider cryptocurrency ecosystem. Optimism operates on the principle of impact=profit, the idea that individuals who positively impact the Collective should be proportionally rewarded with profit. Change the incentives and you change the world.

In this repository, you'll find numerous core components of the OP Stack, the decentralized software stack maintained by the Optimism Collective that powers Optimism and forms the backbone of blockchains like OP Mainnet and Base. Designed to be "aggressively open source," the OP Stack encourages you to explore, modify, extend, and test the code as needed. Although not all elements of the OP Stack are contained here, many of its essential components can be found within this repository. By collaborating on free, open software and shared standards, the Optimism Collective aims to prevent siloed software development and rapidly accelerate the development of the Ethereum ecosystem. Come contribute, build the future, and redefine power, together.



If you're interested in the technical details of how Optimism works, refer to the Optimism Protocol Specification.


General discussion happens most frequently on the Optimism discord. Governance discussion can also be found on the Optimism Governance Forum.


Read through for a general overview of the contributing process for this repository. Use the Developer Quick Start to get your development environment set up to start working on the Optimism Monorepo. Then check out the list of Good First Issues to find something fun to work on! Typo fixes are welcome; however, please create a single commit with all of the typo fixes & batch as many fixes together in a PR as possible. Spammy PRs will be closed.

Security Policy and Vulnerability Reporting

Please refer to the canonical Security Policy document for detailed information about how to report vulnerabilities in this codebase. Bounty hunters are encouraged to check out the Optimism Immunefi bug bounty program. The Optimism Immunefi program offers up to $2,000,042 for in-scope critical vulnerabilities.

Directory Structure

├── docs: A collection of documents including audits and post-mortems
├── op-batcher: L2-Batch Submitter, submits bundles of batches to L1
├── op-bindings: Go bindings for Bedrock smart contracts.
├── op-bootnode: Standalone op-node discovery bootnode
├── op-chain-ops: State surgery utilities
├── op-challenger: Dispute game challenge agent
├── op-e2e: End-to-End testing of all bedrock components in Go
├── op-heartbeat: Heartbeat monitor service
├── op-node: rollup consensus-layer client
├── op-preimage: Go bindings for Preimage Oracle
├── op-program: Fault proof program
├── op-proposer: L2-Output Submitter, submits proposals to L1
├── op-service: Common codebase utilities
├── op-ufm: Simulations for monitoring end-to-end transaction latency
├── op-wheel: Database utilities
├── ops: Various operational packages
├── ops-bedrock: Bedrock devnet work
├── packages
│   ├── chain-mon: Chain monitoring services
│   ├── common-ts: Common tools for building apps in TypeScript
│   ├── contracts-bedrock: Bedrock smart contracts
│   ├── contracts-ts: ABI and Address constants
│   ├── core-utils: Low-level utilities that make building Optimism easier
│   ├── fee-estimation: Tools for estimating gas on OP chains
│   ├── sdk: provides a set of tools for interacting with Optimism
│   └── web3js-plugin: Adds functions to estimate L1 and L2 gas
├── proxyd: Configurable RPC request router and proxy
├── specs: Specs of the rollup starting at the Bedrock upgrade
└── ufm-test-services: Runs a set of tasks to generate metrics

Development and Release Process


Please read this section if you're planning to fork this repository, or make frequent PRs into this repository.

Production Releases

Production releases are always tags, versioned as <component-name>/v<semver>. For example, an op-node release might be versioned as op-node/v1.1.2, and smart contract releases might be versioned as op-contracts/v1.0.0. Release candidates are versioned in the format op-node/v1.1.2-rc.1. We always start with rc.1 rather than rc.

For contract releases, refer to the GitHub release notes for a given release, which will list the specific contracts being released—not all contracts are considered production ready within a release, and many are under active development.

Tags of the form v<semver>, such as v1.1.4, indicate releases of all Go code only, and DO NOT include smart contracts. This naming scheme is required by Golang. In the above list, this means these v<semver releases contain all op-* components, and exclude all contracts-* components.

op-geth embeds upstream geth’s version inside it’s own version as follows: vMAJOR.GETH_MAJOR GETH_MINOR GETH_PATCH.PATCH. Basically, geth’s version is our minor version. For example if geth is at v1.12.0, the corresponding op-geth version would be v1.101200.0. Note that we pad out to three characters for the geth minor version and two characters for the geth patch version. Since we cannot left-pad with zeroes, the geth major version is not padded.

See the Node Software Releases page of the documentation for more information about releases for the latest node components. The full set of components that have releases are:

  • chain-mon
  • ci-builder
  • ci-builder
  • indexer
  • op-batcher
  • op-contracts
  • op-challenger
  • op-heartbeat
  • op-node
  • op-proposer
  • op-ufm
  • proxyd
  • ufm-metamask

All other components and packages should be considered development components only and do not have releases.

Development branch

The primary development branch is develop. develop contains the most up-to-date software that remains backwards compatible with the latest experimental network deployments. If you're making a backwards compatible change, please direct your pull request towards develop.

Changes to contracts within packages/contracts-bedrock/src are usually NOT considered backwards compatible. Some exceptions to this rule exist for cases in which we absolutely must deploy some new contract after a tag has already been fully deployed. If you're changing or adding a contract and you're unsure about which branch to make a PR into, default to using a feature branch. Feature branches are typically used when there are conflicts between 2 projects touching the same code, to avoid conflicts from merging both into develop.


All other files within this repository are licensed under the MIT License unless stated otherwise.