head to head · open source
conductor vs haystack
conductor has 32,207 GitHub stars, 1,010 forks, 253 open issues and last shipped yesterday. haystack has 26,531 stars, 3,144 forks, 143 open issues and last shipped yesterday. conductor leads on adoption by 21% (32,207 vs 26,531 stars). conductor is written in Java under Apache-2.0; haystack is written in Python under Apache-2.0. conductor has attracted 3% as many forks as stars, haystack 12%. conductor 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
| conductor | haystack | |
|---|---|---|
| GitHub stars | ★ 32K | ★ 27K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Java | Python |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 1.0K | ⑂ 3.1K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick conductor if
- You weight community size — 32K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick haystack if
- You want the haystack 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 haystack fits your workflow better
About conductor
Conductor is an Apache 2.0 licensed, event driven agentic workflow engine written in Java that provides durable and highly resilient execution for applications and AI agents, aimed at teams running microservices, AI agents, and adaptive workflow graphs that need orchestration they can version, inspect, and recover.
read the full conductor overview →
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 →
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Frequently asked questions
Is conductor or haystack more popular?
conductor has 32,207 GitHub stars and haystack has 26,531. conductor has the larger community by that measure.
Are conductor and haystack free?
Both are open source. conductor is licensed under Apache-2.0 and haystack under Apache-2.0. Neither carries a licence fee.
What is the difference between conductor and haystack?
conductor is written in Java and haystack 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, conductor or haystack?
Choose conductor if you want the larger community (32,207 stars) or its Apache-2.0 licence terms. Choose haystack if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.