act vs Dagger
A side-by-side comparison of two self-hosted ci/cd & build options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | act | Dagger |
|---|---|---|
| Deploy effort | Read-the-docs project | Under-an-hour setup |
| Health score | 98 · Excellent | 95 · Excellent |
| Category | CI/CD & Build | CI/CD & Build |
| License | MIT | Apache-2.0 |
| Language | Go | Go |
| Setup difficulty | Easy | Medium |
| Min. RAM | 256 MB | 1,024 MB |
| Deployment | bare-metal, binary | docker, binary |
| GitHub stars | ★ 72,082 | ★ 16,294 |
| First released | 2019 | 2022 |
| Replaces | GitHub Actions | GitHub Actions, CircleCI |
What are act and Dagger?
act
act lets developers run GitHub Actions workflows on their own machine using Docker, providing fast local feedback before pushing. It reads the same workflow files used by GitHub so behavior closely matches CI.
- Local GitHub Actions runs
- Docker-based execution
- Reuses workflow files
- Fast feedback loop
Dagger
Dagger is an open-source CI/CD engine that lets developers define pipelines as code in their preferred language and run them anywhere with a containerized engine. It can be self-hosted to power portable build pipelines.
- Pipelines as code
- Runs anywhere with containers
- Multi-language SDKs
- Built-in caching
act vs Dagger: key differences
Both projects are written in Go. Licensing differs — MIT for act versus Apache-2.0 for Dagger. Act is the lighter option, starting around 256 MB of RAM against 1,024 MB for Dagger. Act is the more established project (first released 2019), while Dagger arrived in 2022. Act has the considerably larger community, at 72,082 GitHub stars versus 16,294. Dagger lists first-class Docker deployment; act does not.
Why pick each one
Choose act if…
- Test CI before pushing
- Saves CI minutes
Watch out for
- Not all actions supported
- Docker required
Choose Dagger if…
- Pipelines as real code
- Runs identically anywhere
- Container-level caching
Watch out for
- New concepts to learn
- Container runtime required
Frequently asked questions
Is act or Dagger better?
act is the stronger all-round pick: it has both the larger community and the simpler easy setup. Consider Dagger if its specific feature set fits your needs better.
Are act and Dagger free and open-source?
Yes. act is licensed under MIT and Dagger under Apache-2.0. Both can be self-hosted at no software cost.
Can I run act and Dagger with Docker?
act: check the project docs for container support. Dagger: yes.
Which is lighter on resources, act or Dagger?
act has the smaller minimum footprint at 256 MB of RAM, compared to about 1,024 MB for Dagger. Real-world usage depends on library size, user count, and enabled features.