Comment by CMLewis

OpenSearch provides general search infrastructure and they recently added vector search. It's a low level engine so users would still need to build their own ingestion, parsing, chunking, embeddings, re-ranking, permissions, etc.

Onyx, Sana, and Glean are closer to application-layer enterprise AI products. Their internal knowledge assistants can search across SaaS tools but the interface is more graphical and seats are purchased as end-user software.

Captain sits in between because it's an API-first retrieval system to fully-manage file workloads. This adds search capabilities to existing AI agents but the agents are managed by the developers, outside of Captain.

Kore.ai however is more of an agent platform. Their focus is building and orchestrating agent workflows (which can include document retrieval, but that's not their main focus).