Overview
Open Index is an open-source tool for building structured, domain-specific context that AI agents can actually operate on. Instead of leaving an agent with a pile of documents, Open Index organizes domain knowledge into schemas, entities, connectors, and searchable indexes that can be queried, validated, and exposed through MCP.
The project is aimed at developers building agents for specialized domains such as legal, marketing, support, sales, and infrastructure. These agents often fail because their context is loose, stale, or inconsistently formatted. Open Index addresses that by turning documents and domain objects into an explicit context graph.
Open Index launched on Product Hunt on August 19, 2026, with the tagline "Build a structured, MCP-ready context brain for AI agents." It is worth publishing because it is an MIT-licensed infrastructure tool for agent memory and retrieval, not just another wrapper around a chat model.
Key Features
Structured context graph - Model domain knowledge through primitives such as
doc_type,doc_schema,entity, andconnector.Domain-specific indexing - Build accurate structured data for legal, marketing, support, sales, infrastructure, and other specialized agent contexts.
CLI workflow - Commands include
init,add-doc-type,add-entity,import,index,validate,ingest,run,search,ui,mcp,serve, andmcp-config.MCP support - Serve indexed context to AI agents through Model Context Protocol, including read/write context patterns and read-only mode.
Validation tools - Validate that structured data stays correct as source documents and domain objects change.
Search backends - Uses SQLite FTS5 by default and supports OpenSearch for larger search deployments.
Open-source license - The repository is MIT licensed, making it straightforward for teams to inspect, modify, and self-host.
Pricing & Plans
Open Index is free and open source under the MIT license.
| Cost Area | Price | Notes |
|---|---|---|
| Open Index software | $0 | MIT-licensed GitHub repository |
| Local storage | $0 if self-hosted locally | SQLite FTS5 is the default backend |
| Search infrastructure | Varies | OpenSearch or hosted infrastructure costs depend on deployment choice |
| LLM usage | Varies | Any model/API costs come from the agent stack that uses Open Index |
The software itself is free, but production deployments may still incur database, search, hosting, observability, or model-provider costs.
Best For
- Developers building domain-specialized AI agents
- Teams that need structured retrieval rather than generic document chunks
- Agent projects adopting MCP for context access
- Infrastructure and support teams modeling runbooks, incidents, tickets, or systems as structured entities
- Builders who want open-source AI data analysis and context tooling they can inspect and self-host
FAQ
What is Open Index?
Open Index is an open-source tool for building structured, domain-specific context graphs that AI agents can search, validate, update, and access through MCP.
Is Open Index free?
Yes. Open Index is MIT licensed and free to use. Deployment infrastructure and LLM usage may still cost money depending on how you run it.
What does Open Index store?
It stores structured domain context built from document types, schemas, entities, connectors, and indexed data.
Does Open Index support MCP?
Yes. The README includes MCP-related commands and positions Open Index as a context layer that agents can access through Model Context Protocol.
Who should use Open Index?
Open Index is best for developers building specialized agents that need reliable structured knowledge rather than loose prompt context or generic document search.