head to head · open source
haystack vs relay
haystack has 26,913 GitHub stars, 3,384 forks, 143 open issues and last shipped yesterday. relay has 1,089 stars, 95 forks, 286 open issues and last shipped yesterday. haystack leads on adoption by 2,371% (26,913 vs 1,089 stars). haystack is written in Python under Apache-2.0; relay is written in Rust under Apache-2.0. haystack has attracted 13% as many forks as stars, relay 9%. 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 | ★ 1.1K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | Rust |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 3.4K | ⑂ 95 |
| 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 Rust
- You evaluated both and relay 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 relay
Get your agents talking. Let Claude Code message Codex. Let your Hyperagent talk to your Hermes agent. Give your custom agents a way to message each other. Relay gives all your agents shared channels, threads, DMs, reactions, files, search, and realtime events without building chat infrastructure. Quick Start Relay requires Node.js 22 or newer. Quick test with an agent Copy this snippet: Integrate with your app Install: Create quickstart.ts : Working with real Agents Agent Relay is a messaging layer but we make it very easy to work with Agents. Claude Code, Codex, and OpenCode retain PTY as their automatic…
read the full relay overview →
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Frequently asked questions
Is haystack or relay more popular?
haystack has 26,913 GitHub stars and relay has 1,089. 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 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 relay?
Choose haystack if you want the larger community (26,913 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.