OpenZeppelin Contracts is a library for secure smart contract development.
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 
Go to file
Antonio Viggiano 7e7060e00e
Update IERC3156FlashBorrower.sol (#4145)
21 hours ago
.changeset Add FV specification for ERC20Wrapper (#4100) 3 weeks ago
.github Limit concurrency of formal-verification runs 3 weeks ago
audits Update guidelines and project documentation (#3966) 2 months ago
certora Add Pausable FV (#4117) 2 weeks ago
contracts Update IERC3156FlashBorrower.sol (#4145) 21 hours ago
docs Clarify Governor Bravo compatibility scope (#4090) 2 weeks ago
hardhat Use Prettier for JS files (#3913) 3 months ago
lib Bump and pin Forge Std submodule (#4102) 3 weeks ago
scripts Add a "fees" section to the ERC4626 guide (#4054) 1 month ago
test Make AccessControlDefaultAdminRules delay configurable (#4079) 5 days ago
.codecov.yml Remove Codecov Patch status outside PRs 7 months ago
.editorconfig Remove line length configuration for markdown files 8 months ago
.eslintrc Simplify ESLint config (#3903) 3 months ago
.gitignore Add Pausable FV (#4117) 2 weeks ago
.gitmodules Bump and pin Forge Std submodule (#4102) 3 weeks ago
.mocharc.js Use Hardhat recommended Mocha configuration (#2805) 2 years ago
.prettierrc Use Prettier for JS files (#3913) 3 months ago
.solcover.js Use Prettier for JS files (#3913) 3 months ago
.solhint.json remove duplicated 'private-vars-leading-underscore' solhint rule (#2800) 2 years ago
CHANGELOG.md Merge release-v4.8 branch 4 weeks ago
CODE_OF_CONDUCT.md Update guidelines and project documentation (#3966) 2 months ago
CONTRIBUTING.md Add `RELEASING.md` docs (#3981) 1 month ago
GUIDELINES.md Add guidelines for pull requests (#4002) 2 months ago
LICENSE Update guidelines and project documentation (#3966) 2 months ago
README.md Fix typo in README (#4129) 1 week ago
RELEASING.md Add `RELEASING.md` docs (#3981) 1 month ago
SECURITY.md Update guidelines and project documentation (#3966) 2 months ago
foundry.toml Add ERC4626 standard property tests (#3792) 5 months ago
hardhat.config.js Add storageLayout to outputSelection 2 months ago
logo.svg use svg logo for better scaling 3 years ago
netlify.toml Fix documentation previews in pull requests (#2015) 3 years ago
package-lock.json Update lockfile (#4080) 3 weeks ago
package.json Formal verification using Certora (#4084) 4 weeks ago
renovate.json Update renovate.json 2 months ago
requirements.txt Update dependency certora-cli to v3.6.4 (#4110) 3 weeks ago
slither.config.json Ignore reentrancy in`executeBatch` and update Slither config (#3955) 3 months ago

README.md

OpenZeppelin

NPM Package Coverage Status GitPOAPs Docs Forum

A library for secure smart contract development. Build on a solid foundation of community-vetted code.

🧙 Not sure how to get started? Check out Contracts Wizard — an interactive smart contract generator.

🏗️ Want to scale your decentralized application? Check out OpenZeppelin Defender — a secure platform for automating and monitoring your operations.

Overview

Installation

$ npm install @openzeppelin/contracts

OpenZeppelin Contracts features a stable API, which means that your contracts won't break unexpectedly when upgrading to a newer minor version.

An alternative to npm is to use the GitHub repository (openzeppelin/openzeppelin-contracts) to retrieve the contracts. When doing this, make sure to specify the tag for a release such as v4.5.0, instead of using the master branch.

Usage

Once installed, you can use the contracts in the library by importing them:

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";

contract MyCollectible is ERC721 {
    constructor() ERC721("MyCollectible", "MCO") {
    }
}

If you're new to smart contract development, head to Developing Smart Contracts to learn about creating a new project and compiling your contracts.

To keep your system secure, you should always use the installed code as-is, and neither copy-paste it from online sources nor modify it yourself. The library is designed so that only the contracts and functions you use are deployed, so you don't need to worry about it needlessly increasing gas costs.

Learn More

The guides in the documentation site will teach about different concepts, and how to use the related contracts that OpenZeppelin Contracts provides:

  • Access Control: decide who can perform each of the actions on your system.
  • Tokens: create tradeable assets or collectives, and distribute them via Crowdsales.
  • Utilities: generic useful tools including non-overflowing math, signature verification, and trustless paying systems.

The full API is also thoroughly documented, and serves as a great reference when developing your smart contract application. You can also ask for help or follow Contracts's development in the community forum.

Finally, you may want to take a look at the guides on our blog, which cover several common use cases and good practices. The following articles provide great background reading, though please note that some of the referenced tools have changed, as the tooling in the ecosystem continues to rapidly evolve.

Security

This project is maintained by OpenZeppelin with the goal of providing a secure and reliable library of smart contract components for the ecosystem. We address security through risk management in various areas such as engineering and open source best practices, scoping and API design, multi-layered review processes, and incident response preparedness.

The security policy is detailed in SECURITY.md, and specifies how you can report security vulnerabilities, which versions will receive security patches, and how to stay informed about them. We run a bug bounty program on Immunefi to reward the responsible disclosure of vulnerabilities.

The engineering guidelines we follow to promote project quality can be found in GUIDELINES.md.

Past audits can be found in audits/.

Smart contracts are a nascent technology and carry a high level of technical risk and uncertainty. Although OpenZeppelin is well known for its security audits, using OpenZeppelin Contracts is not a substitute for a security audit.

OpenZeppelin Contracts is made available under the MIT License, which disclaims all warranties in relation to the project and which limits the liability of those that contribute and maintain the project, including OpenZeppelin. As set out further in the Terms, you acknowledge that you are solely responsible for any use of OpenZeppelin Contracts and you assume all risks associated with any such use.

Contribute

OpenZeppelin Contracts exists thanks to its contributors. There are many ways you can participate and help build high quality software. Check out the contribution guide!

License

OpenZeppelin Contracts is released under the MIT License.

Your use of this Project is governed by the terms found at www.openzeppelin.com/tos (the "Terms").