head to head · open source
PageIndex vs LangWatch
PageIndex has 35,765 GitHub stars, 3,152 forks, 103 open issues and last shipped 2 days ago. LangWatch has 4,833 stars, 395 forks, 939 open issues and last shipped 2 days ago. PageIndex leads on adoption by 640% (35,765 vs 4,833 stars). PageIndex is written in Python under MIT; LangWatch is written in TypeScript under Apache-2.0. PageIndex has attracted 9% as many forks as stars, LangWatch 8%. LangWatch was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ai, llm), 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
| PageIndex | LangWatch | |
|---|---|---|
| GitHub stars | ★ 36K | ★ 4.8K |
| License | MIT | Apache-2.0 |
| Written in | Python | TypeScript |
| Last push | 2026-09-19 | 2026-09-19 |
| Forks | ⑂ 3.2K | ⑂ 395 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick PageIndex if
- You weight community size — 36K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick LangWatch if
- You want the LangWatch 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 LangWatch fits your workflow better
About PageIndex
PageIndex is a vectorless, reasoning based retrieval augmented generation engine written in Python and released under the MIT license. It lives in the AI and machine learning infrastructure ecosystem, with topics spanning RAG, information retrieval, LLM reasoning, context engineering, and agentic AI. Instead of building a vector index, PageIndex generates a hierarchical tree index for each document and then lets a large language model reason its way through that tree, in the same way a human expert turns to the right section of a long report. The project ships as a Python SDK, a hosted cloud service, and a docume…
read the full PageIndex overview →
About LangWatch
LangWatch is an open source TypeScript platform for LLM evaluations and AI agent testing, licensed under Apache 2.0. It lives in the machine learning infrastructure ecosystem for teams that build LLM powered agents and need to test, simulate, evaluate, and monitor agents before release and in production.
read the full LangWatch overview →
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Frequently asked questions
Is PageIndex or LangWatch more popular?
PageIndex has 35,765 GitHub stars and LangWatch has 4,833. PageIndex has the larger community by that measure.
Are PageIndex and LangWatch free?
Both are open source. PageIndex is licensed under MIT and LangWatch under Apache-2.0. Neither carries a licence fee.
What is the difference between PageIndex and LangWatch?
PageIndex is written in Python and LangWatch 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, PageIndex or LangWatch?
Choose PageIndex if you want the larger community (35,765 stars) or its MIT licence terms. Choose LangWatch if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.