head to head · open source
haystack vs harmonist
haystack has 26,924 GitHub stars, 3,388 forks, 143 open issues and last shipped yesterday. harmonist has 2,244 stars, 209 forks, 1 open issues and last shipped 5 months ago. haystack leads on adoption by 1,100% (26,924 vs 2,244 stars). haystack is written in Python under Apache-2.0; harmonist is written in Python under MIT. haystack has attracted 13% as many forks as stars, harmonist 9%. haystack was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (agent-framework, 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
| haystack | harmonist | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 2.2K |
| License | Apache-2.0 | MIT |
| Written in | Python | Python |
| Last push | 2026-11-04 | 2026-06-09 |
| Forks | ⑂ 3.4K | ⑂ 209 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick haystack if
- You weight community size — 27K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Python
- 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 haystack
🎉🎊✨ Haystack 3.0 is out! ✨🎊🎉 Read the announcement here! 🥳 🎈 🎆 🪅 🎇 🍾 🥂 🎁 🌈 Haystack is an open source AI orchestration framework for building production ready LLM applications in Python. Design modular pipelines and agent workflows with explicit control over retrieval, routing, memory, and generation. Build scalable RAG systems, multimodal applications, semantic search, question answering, and autonomous agents, all in a transparent architecture that lets you experiment, customize deeply, and deploy with confidence. Table of Contents Installation Documentation Features Haystack Enterprise: Support &…
read the full haystack 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 haystack or harmonist more popular?
haystack has 26,924 GitHub stars and harmonist has 2,244. haystack has the larger community by that measure.
Are haystack and harmonist free?
Both are open source. haystack is licensed under Apache-2.0 and harmonist under MIT. Neither carries a licence fee.
What is the difference between haystack and harmonist?
haystack is written in Python 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, haystack or harmonist?
Choose haystack if you want the larger community (26,924 stars) or its Apache-2.0 licence terms. Choose harmonist if its feature set, stack or MIT licence fits better. Both are self-hostable.