head to head · open source
haystack vs atom
haystack has 26,559 GitHub stars, 3,153 forks, 143 open issues and last shipped yesterday. atom has 901 stars, 94 forks, 2 open issues and last shipped 2 days ago. haystack leads on adoption by 2,848% (26,559 vs 901 stars). haystack is written in Python under Apache-2.0; atom is written in Python under AGPL-3.0. haystack has attracted 12% as many forks as stars, atom 10%. haystack was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (ai), 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 | atom | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 901 |
| License | Apache-2.0 | AGPL-3.0 |
| Written in | Python | Python |
| Last push | 2026-09-19 | 2026-09-18 |
| Forks | ⑂ 3.2K | ⑂ 94 |
| 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 atom if
- You want the atom feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Python
- You evaluated both and atom fits your workflow better
About haystack
Haystack is an open source AI orchestration framework written in Python under the Apache 2.0 licence, for building context engineered, production ready large language model applications as modular pipelines and agent workflows with explicit control over retrieval, routing, memory, and generation, and it is aimed at developers and teams building scalable agents, retrieval augmented generation, multimodal applications, semantic search, question answering, and conversational systems.
read the full haystack overview →
About atom
Atom Agent is an open source, self hosted AI agent workforce platform, licensed AGPL 3.0 and written in Python, that lets teams delegate routine work to specialty agents under default on governance checks — and it is aimed at organisations that want agent accountability, verifiable outcomes, and data ownership on their own hardware.
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Frequently asked questions
Is haystack or atom more popular?
haystack has 26,559 GitHub stars and atom has 901. haystack has the larger community by that measure.
Are haystack and atom free?
Both are open source. haystack is licensed under Apache-2.0 and atom under AGPL-3.0. Neither carries a licence fee.
What is the difference between haystack and atom?
haystack is written in Python and atom 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 atom?
Choose haystack if you want the larger community (26,559 stars) or its Apache-2.0 licence terms. Choose atom if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.