head to head · open source
haystack vs Prefect
haystack has 26,913 GitHub stars, 3,384 forks, 143 open issues and last shipped yesterday. Prefect has 24,109 stars, 2,624 forks, 858 open issues and last shipped yesterday. haystack leads on adoption by 12% (26,913 vs 24,109 stars). haystack is written in Python under Apache-2.0; Prefect is written in Python under Apache-2.0. haystack has attracted 13% as many forks as stars, Prefect 11%. Prefect was the more recently maintained of the two, and both are self-hostable with no licence fee.
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 | Prefect | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 24K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | Python |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 3.4K | ⑂ 2.6K |
| 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 Prefect if
- You want the Prefect feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Python
- You evaluated both and Prefect 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 Prefect
Installation · Quickstart · Build workflows · Deploy workflows · Prefect Cloud Prefect Prefect is a workflow orchestration framework for building data pipelines in Python. It's the simplest way to elevate a script into a production workflow. With Prefect, you can build resilient, dynamic data pipelines that react to the world around them and recover from unexpected changes. With just a few lines of code, data teams can confidently automate any data process with features such as scheduling, caching, retries, and event based automations. Workflow activity is tracked and can be monitored with a self hosted Prefect…
read the full Prefect overview →
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Frequently asked questions
Is haystack or Prefect more popular?
haystack has 26,913 GitHub stars and Prefect has 24,109. haystack has the larger community by that measure.
Are haystack and Prefect free?
Both are open source. haystack is licensed under Apache-2.0 and Prefect under Apache-2.0. Neither carries a licence fee.
What is the difference between haystack and Prefect?
haystack is written in Python and Prefect 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 Prefect?
Choose haystack if you want the larger community (26,913 stars) or its Apache-2.0 licence terms. Choose Prefect if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.