head to head · open source
haystack vs moon
haystack has 26,531 GitHub stars, 3,144 forks, 143 open issues and last shipped yesterday. moon has 4,105 stars, 252 forks, 99 open issues and last shipped yesterday. haystack leads on adoption by 546% (26,531 vs 4,105 stars). haystack is written in Python under Apache-2.0; moon is written in Rust under MIT. haystack has attracted 12% as many forks as stars, moon 6%. moon 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 | moon | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 4.1K |
| License | Apache-2.0 | MIT |
| Written in | Python | Rust |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 3.1K | ⑂ 252 |
| 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 moon if
- You want the moon feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Rust
- You evaluated both and moon 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 moon
moon is a repository management, organization, orchestration, and notification tool for the web ecosystem, written in Rust under the MIT license. It is a build system and monorepo management tool whose concepts are heavily inspired by Bazel and other build systems. The project is associated with build system, monorepo tooling, ci cd, Node.js, JavaScript, Bun, Deno, Go, Python, and Ruby topics.
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Frequently asked questions
Is haystack or moon more popular?
haystack has 26,531 GitHub stars and moon has 4,105. haystack has the larger community by that measure.
Are haystack and moon free?
Both are open source. haystack is licensed under Apache-2.0 and moon under MIT. Neither carries a licence fee.
What is the difference between haystack and moon?
haystack is written in Python and moon in Rust. 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 moon?
Choose haystack if you want the larger community (26,531 stars) or its Apache-2.0 licence terms. Choose moon if its feature set, stack or MIT licence fits better. Both are self-hostable.