head to head · open source
Kestra vs harmonist
Kestra has 28,181 GitHub stars, 3,005 forks, 713 open issues and last shipped 2 days ago. harmonist has 2,257 stars, 206 forks, 1 open issues and last shipped 3 months ago. Kestra leads on adoption by 1,149% (28,181 vs 2,257 stars). Kestra is written in Java under Apache-2.0; harmonist is written in Python under MIT. Kestra has attracted 11% 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 | ★ 28K | ★ 2.3K |
| License | Apache-2.0 | MIT |
| Written in | Java | Python |
| Last push | 2026-09-18 | 2026-06-09 |
| Forks | ⑂ 3.0K | ⑂ 206 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Kestra if
- You weight community size — 28K 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
Kestra is an open source, event driven orchestration platform for data, AI, and infrastructure workflows. It operates in the Java based ecosystem and is licensed under Apache 2.0. The project provides a unified interface for both scheduled and real time automation, supporting declarative workflow definitions in YAML while also offering visual and AI assisted authoring.
read the full Kestra overview →
About harmonist
harmonist is an MIT licensed, dependency free Python framework that adds multi agent orchestration and mechanically enforced protocol to AI coding assistants such as Cursor, Claude Code, Copilot, Windsurf, and Aider, and it serves individual developers and teams who need agent workflows to obey engineering rules rather than merely be asked to follow them.
read the full harmonist overview →
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Frequently asked questions
Is Kestra or harmonist more popular?
Kestra has 28,181 GitHub stars and harmonist has 2,257. 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 (28,181 stars) or its Apache-2.0 licence terms. Choose harmonist if its feature set, stack or MIT licence fits better. Both are self-hostable.