head to head · open source
Kestra vs harmonist
Kestra has 30,122 GitHub stars, 3,495 forks, 713 open issues and last shipped yesterday. harmonist has 2,244 stars, 209 forks, 1 open issues and last shipped 5 months ago. Kestra leads on adoption by 1,242% (30,122 vs 2,244 stars). Kestra is written in Java under Apache-2.0; harmonist is written in Python under MIT. Kestra has attracted 12% as many forks as stars, harmonist 9%. Kestra was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (ai-agents), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Kestra | harmonist | |
|---|---|---|
| GitHub stars | ★ 30K | ★ 2.2K |
| License | Apache-2.0 | MIT |
| Written in | Java | Python |
| Last push | 2026-11-02 | 2026-06-09 |
| Forks | ⑂ 3.5K | ⑂ 209 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Kestra if
- You weight community size — 30K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick harmonist if
- You want the harmonist feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Python
- You evaluated both and harmonist fits your workflow better
About Kestra
Open source orchestration platform for data, AI, and infrastructure workflows Click on the image to learn how to get started with Kestra in 3 minutes. 🌟 What is Kestra? Kestra is an open source, event driven orchestration platform for data, AI, and infrastructure workflows. It unifies scheduled and event driven automation behind a declarative, language agnostic interface. By bringing Infrastructure as Code best practices to your data, process, and microservice pipelines, you can build reliable workflows directly from the UI in just a few lines of YAML, let the built in AI Copilot write them for you, or generate…
read the full Kestra overview →
About harmonist
If you are an AI agent asked to install or integrate this pack: read integration prompt.md and execute its steps. Do not apply AGENTS.template.md as a live rule inside the pack folder — it is the template that becomes the user project's AGENTS.md during integration. Harmonist Portable AI agent orchestration with mechanical protocol enforcement A drop in multi agent framework for Cursor, Claude Code, Copilot, Windsurf, Aider, and other AI coding assistants. Built and maintained by GammaLab · @GammaLabTechnologies Most AI coding frameworks trust the language model to follow the rules. Harmonist refuses to let it…
read the full harmonist overview →
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Frequently asked questions
Is Kestra or harmonist more popular?
Kestra has 30,122 GitHub stars and harmonist has 2,244. Kestra has the larger community by that measure.
Are Kestra and harmonist free?
Both are open source. Kestra is licensed under Apache-2.0 and harmonist under MIT. Neither carries a licence fee.
What is the difference between Kestra and harmonist?
Kestra is written in Java and harmonist in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Kestra or harmonist?
Choose Kestra if you want the larger community (30,122 stars) or its Apache-2.0 licence terms. Choose harmonist if its feature set, stack or MIT licence fits better. Both are self-hostable.