act Review (2026): Pricing, Features & Honest Verdict

TLDR

act lets you run GitHub Actions workflows locally using Docker, so you can test and debug CI pipelines without pushing to GitHub. With 56K+ stars, it’s become essential for Actions-heavy teams. Best for: developers testing GitHub Actions locally. Price: free and open source. Rating: 7.8/10

What is act?

act is an open source command-line tool that runs your GitHub Actions workflows on your local machine using Docker. Instead of pushing a commit, waiting for GitHub to spin up a runner, and then reading through logs to find out your workflow broke on step 14, you just type act in your terminal and get instant feedback.

The project by nektos has collected over 56,000 GitHub stars, making it one of the most popular developer tools on the platform. It reads your .github/workflows/ directory, parses the YAML, and executes each job in Docker containers that mimic GitHub’s runner environment.

Key Features

Local Workflow Execution

Run any GitHub Actions workflow locally with a single command. act reads your workflow YAML, resolves action references, and executes steps in Docker containers. You see output in real time, just like watching a CI run, but without the 30-second queue wait.

Event Simulation

Trigger workflows with different GitHub events. Test your push, pull_request, workflow_dispatch, and other event types by passing event payloads. This lets you verify conditional logic and event-specific behavior without creating actual GitHub events.

Docker-Based Runners

act uses Docker images that approximate GitHub’s hosted runners. The default micro image is fast to download. Medium and large images offer closer parity with the actual GitHub runner environment, including pre-installed tools and system packages.

Secret and Variable Management

Pass secrets via .secrets files, environment variables, or command-line flags. act supports .env files for variables and .secrets for sensitive values, keeping your local testing environment configured the same way as production CI.

Selective Job Execution

Run specific jobs or workflows instead of the entire pipeline. Use act -j job-name to target a single job, or act -W .github/workflows/specific.yml to run one workflow file. This targeted execution saves time when you only need to debug one piece.

Pricing

act is completely free and open source under the MIT license. No paid tiers, no premium features behind a paywall. You need Docker installed locally, which is also free for personal and small business use.

Pros

• Eliminates the push-wait-debug cycle for GitHub Actions development
• Massive community backing with 56K+ GitHub stars and active maintenance
• Single binary installation, no complex setup required
• Supports secrets, variables, matrices, and most workflow features
• Dramatically speeds up workflow development and debugging

Cons

• Not 100% compatible with GitHub’s runner environment, some actions behave differently
• Docker image sizes can be large if you need full runner parity
• Actions that rely on GitHub API calls may fail or need mocking
• Composite actions and some newer Actions features have incomplete support

Who Should Use act?

Any developer who writes or maintains GitHub Actions workflows. Solo developers benefit from faster iteration cycles. Teams benefit from catching workflow errors before they hit the shared CI queue. If you’ve ever committed “fix CI” five times in a row, act will change your life.

Alternatives

GitHub Actions

The platform act is designed to complement, not replace. GitHub Actions runs in the cloud with full API access and marketplace integrations. act gives you the local testing layer that GitHub’s own tooling lacks.

Dagger

A programmable CI/CD engine that lets you define pipelines in Go, Python, or TypeScript. Dagger runs locally and in CI, solving the same “test before push” problem but with a different approach: code instead of YAML.

Earthly

Combines Dockerfiles and Makefiles into reproducible build definitions. Like act, it runs locally first. Unlike act, it’s not tied to GitHub Actions syntax, so it works as a standalone CI tool across any platform.

FAQ

Does act support all GitHub Actions?

Most actions work, but not all. Actions that make GitHub API calls, use hosted runner-specific features, or rely on GitHub’s network environment may need adjustments. The core workflow syntax (steps, jobs, matrices, conditions) is well supported.

How much disk space does act need?

The micro runner image is about 200MB. The medium image is around 2GB. The full large image that closely matches GitHub’s runner is 10GB+. You can start with micro and upgrade only if you need closer parity.

Can I use act in CI itself?

Technically yes, but it’s not the intended use case. act shines as a local development tool. Running act inside CI to test workflows would be circular. Some teams do use it in CI for validating workflow syntax though.

Verdict

act solves a genuine pain point that every GitHub Actions user has felt: the slow, tedious cycle of pushing commits just to test CI changes. At 56K+ stars, the community has spoken clearly about its value. The compatibility gaps are real but shrinking with each release. At 7.8/10, act is a must-have tool for anyone serious about GitHub Actions development. The time it saves on the first day pays for the setup effort ten times over.