act

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Introduction

act lets you run your GitHub Actions locally. It reads the workflow files in .github/workflows/, works out which jobs to run, pulls or builds the needed Docker images, and executes the steps in containers that mimic GitHub’s runners.

The two benefits the project highlights are fast feedback, because you no longer need to commit and push to test a workflow change, and using workflows as a local task runner instead of maintaining a separate Makefile. You can pick an event, a job or a workflow, pass secrets and inputs, and choose runner images of different sizes.

In the quality loop act shortens the feedback cycle for the CI pipeline itself.

The source code is at nektos/act on GitHub under the MIT licence, with about 72,600 stars; the most recent commit was on 4 November 2026.

Features

1. Local runs: Execute workflows in Docker on your machine.
2. Event selection: Simulate push, pull_request and other events.
3. Job filtering: Run one job or workflow.
4. Secrets and inputs: Pass values from files or flags.
5. Runner images: Small, medium and large image options.
6. Matrix support: Run matrix jobs locally.

Pros

1. Faster iteration: Debug workflows without commit-push cycles.
2. Free to use: Open source under the MIT licence, so the core tool costs nothing to use.
3. Actively maintained: The repository had commits as recent as 4 November 2026.
4. Community: About 72,600 GitHub stars.

Cons

1. Not identical to GitHub: Some runner features and services behave differently.
2. Docker required: Needs a container runtime.
3. Large images: Full runner images are big downloads.

Usage and Links (Example)

act -l                      # list jobs
act pull_request -j test    # run the test job for a PR event
act -s GITHUB_TOKEN="$(gh auth token)"

Resources:

• act website
• GitHub repository

Pricing

act is free and open source under the MIT licence.

Recommended for?

1. Developers editing GitHub Actions workflows.
2. Teams that want to reuse workflows as local task runners.

Conclusion

act takes much of the guesswork out of changing CI workflows.

Expect small differences from hosted runners, and confirm critical changes on GitHub.

On CheckOps, act is filed under the Release & CI gates stage. Related tools listed here include actionlint, zizmor, OpenSSF Scorecard, pre-commit, Super-Linter and Gitleaks. When comparing them, weigh the licence, the languages and platforms each supports, whether it is self-hosted or managed, and how cleanly it slots into your existing CI pipeline. Details on this page were checked against the official website, documentation and repository on 11 November 2026.