R2R
RAG & knowledgeAn open-source "RAG to riches" engine with ingestion, retrieval, and agentic search built in.
R2R is a RAG engine that ships the whole stack behind a clean API: document ingestion, retrieval, knowledge-graph construction, user management, and an agentic search mode that reasons over multiple retrieval steps.
It is built to be deployed as a retrieval service that an application calls, rather than a library you assemble.
Where it's ideally used
A fit when you want a deployable retrieval service — API, ingestion, and agentic search included — rather than a toolkit.
Where it doesn't fit
Running it as a service is more than you need for a small embedded retrieval feature.