head to head · open source
haystack vs relay
haystack has 26,559 GitHub stars, 3,153 forks, 143 open issues and last shipped yesterday. relay has 843 stars, 65 forks, 286 open issues and last shipped today. haystack leads on adoption by 3,051% (26,559 vs 843 stars). haystack is written in Python under Apache-2.0; relay is written in TypeScript under Apache-2.0. haystack has attracted 12% as many forks as stars, relay 8%. relay was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (agentic-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 | relay | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 843 |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | TypeScript |
| Last push | 2026-09-19 | 2026-09-20 |
| Forks | ⑂ 3.2K | ⑂ 65 |
| 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 relay if
- You want the relay feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches TypeScript
- You evaluated both and relay 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 relay
Relay is a TypeScript, Apache 2.0 licensed real time messaging layer that gives AI agents shared channels, threads, direct messages, reactions, files, search and realtime events, and it is built for teams orchestrating multiple agents such as Claude Code, Codex or custom harnesses.
read the full relay overview →
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Frequently asked questions
Is haystack or relay more popular?
haystack has 26,559 GitHub stars and relay has 843. haystack has the larger community by that measure.
Are haystack and relay free?
Both are open source. haystack is licensed under Apache-2.0 and relay under Apache-2.0. Neither carries a licence fee.
What is the difference between haystack and relay?
haystack is written in Python and relay in TypeScript. 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 relay?
Choose haystack if you want the larger community (26,559 stars) or its Apache-2.0 licence terms. Choose relay if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.