head to head · open source
haystack vs OpenOPC-Shadow-Adapter
haystack has 26,782 GitHub stars, 3,307 forks, 143 open issues and last shipped today. OpenOPC-Shadow-Adapter has 1,844 stars, 1 forks, 0 open issues and last shipped 2 months ago. haystack leads on adoption by 1,352% (26,782 vs 1,844 stars). haystack is written in Python under Apache-2.0; OpenOPC-Shadow-Adapter is written in Python under MIT. haystack has attracted 12% as many forks as stars, OpenOPC-Shadow-Adapter 0%. haystack 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, generative-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 | OpenOPC-Shadow-Adapter | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 1.8K |
| License | Apache-2.0 | MIT |
| Written in | Python | Python |
| Last push | 2026-10-20 | 2026-08-20 |
| Forks | ⑂ 3.3K | ⑂ 1 |
| 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 OpenOPC-Shadow-Adapter if
- You want the OpenOPC-Shadow-Adapter feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Python
- You evaluated both and OpenOPC-Shadow-Adapter 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 OpenOPC-Shadow-Adapter
OpenOPC Shadow Adapter Non Blocking Human in the Loop (HITL) & BYOC Infrastructure for OpenOPC AI Agent Employees For Your Compan The Carbon Silicon Continuum: Real Humans & Remote PCs as First Class OpenOPC Employees Built for OpenOPC Zero Core Modifications Production Release v0.1.0 What is OpenOPC Shadow Adapter? openopc shadow adapter is a high concurrency Temporal Bridge for OpenOPC. It allows OpenOPC agentic DAGs to pause non blockingly when a role requires human sign off (Carbon) or remote GPU execution (Silicon BYOC), without causing engine timeouts or stalling parallel branches. 1. Non Blocking…
read the full OpenOPC-Shadow-Adapter overview →
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Frequently asked questions
Is haystack or OpenOPC-Shadow-Adapter more popular?
haystack has 26,782 GitHub stars and OpenOPC-Shadow-Adapter has 1,844. haystack has the larger community by that measure.
Are haystack and OpenOPC-Shadow-Adapter free?
Both are open source. haystack is licensed under Apache-2.0 and OpenOPC-Shadow-Adapter under MIT. Neither carries a licence fee.
What is the difference between haystack and OpenOPC-Shadow-Adapter?
haystack is written in Python and OpenOPC-Shadow-Adapter 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 OpenOPC-Shadow-Adapter?
Choose haystack if you want the larger community (26,782 stars) or its Apache-2.0 licence terms. Choose OpenOPC-Shadow-Adapter if its feature set, stack or MIT licence fits better. Both are self-hostable.