core

July 28, 2026 · View on GitHub

The core package is the official standard library for the Motoko programming language.

This replaces the original base library, which is available here.

An official migration guide is available for upgrading projects from base to core.

Quick Start

  1. Install the Mops package manager
  2. Open a terminal in your project directory
  3. Run mops add core

This adds the following dependency to your mops.toml config file:

[dependencies]
core = "2.6.1"

Contributing

This repository is currently closed to external contributions. Please feel free to report a bug, ask a question, or request a feature on the project's GitHub issues page.

Interface design and code style guidelines for the repository can be found here.

Dev Environment

Make sure that Node.js >= 22.x is installed on your system.

Run the following commands to configure your local development branch:

# First-time setup
git clone https://github.com/dfinity/motoko-core
cd motoko-core
npm ci
npx ic-mops toolchain init

Below is a quick reference for commonly-used scripts during development:

npm test # Run all tests
npm run format # Format Motoko files
npm run validate:api # Update the public API lockfile
npm run validate:docs Array # Run code snippets in `src/Array.mo`

All available scripts can be found in the project's package.json file.

Major Contributors

Big thanks to the following community contributors: