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OpenCrab

An ontology-centered Graph RAG platform that structures documents into reusable AI knowledge packs.

Source rating 5.0 (66) 4.9k views 4.9k/mo traffic 0 saves Freemium
Ontology Platform Graph RAG Knowledge graph
More categories (4)
Model Context Protocol (MCP) AI Agent Grounding Document Parser Knowledge Management
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Free + from $10 per month (15,000 KRW)

Verdict

A quick read before you dig into the full page.

Best if
An ontology-centered Graph RAG platform that structures documents into reusable AI knowledge packs
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You need enterprise SLAs or a fully managed team plan right away
Pick this when
Freemium · Free + from $10 per month (15,000 KRW)

Overview

OpenCrab is an ontology-centered knowledge platform designed for the AI agent era. It enables experts, researchers, and AI builders to transform scattered documents, notes, workflows, and domain expertise into structured, evidence-backed 'ontology packs.' These packs can be searched, shared, and queried by AI agents using Graph RAG and Model Context Protocol (MCP), grounding AI workflows in verifiable, high-quality knowledge graphs.

OpenCrab screenshot

Access & connections

Where you can use OpenCrab, and what it plugs into.

Platforms

Web

Integrations

Notion GitHub MCP

Capabilities

What this tool accepts, produces, and is strongest at.

Highlights

  • Ontology Pack Creation: Converts scattered documents and expertise into reusable, structured knowledge packs.
  • Graph RAG & MCP Integration: Connects knowledge graphs seamlessly to LLMs and development workspaces via Model Context Protocol.
  • Multi-format Data Ingestion: Supports ingestion of PDFs, HWP files, Notion, GitHub, images (via OCR/CLIP), and web research.
  • 9-Space MetaOntology Structure: Automatically organizes extracted concepts into structured categories like Subject, Evidence, Claim, Policy, and Lever.
  • Expert Marketplace: Provides a dedicated workflow for domain experts to publish, verify, and sell customized ontology packs.

FAQ 5

What is OpenCrab?
OpenCrab is an ontology-centered knowledge platform designed for the AI agent era. It enables experts, researchers, and AI builders to transform scattered documents, notes, workflows, and domain expertise into structured, evidence-backed 'ontology packs.' These packs can be searched, shared, and queried by AI agents using Graph RAG and Model Context Protocol (MCP), grounding AI workflows in verifiable, high-quality knowledge graphs.
How to use OpenCrab?
To use OpenCrab, first ingest unstructured data sources like PDFs, HWP files, URLs, Notion pages, or GitHub repositories. The platform extracts entities, concepts, claims, and relations, structuring them into a 9-space MetaOntology. Once structured, you can query this knowledge graph using Graph RAG, MCP clients, or connected AI tools like Claude, GPT, or Cursor.
What is an ontology pack in OpenCrab?
An ontology pack is a structured, reusable package of knowledge containing entities, nodes, edges, and evidence extracted from documents and workflows that AI agents can easily query and reason over.
Can I ingest my own private documents on the Free plan?
No, the Free plan is restricted to exploring public ontology packs and basic graph searching. To ingest your own documents and create private workspaces, you need to upgrade to the Pro plan ($10/month).
What AI tools can be connected with OpenCrab?
OpenCrab supports integration with popular tools and frameworks like GPT, Claude, Claude Code, Cursor, Antigravity, Hermes Agent, and other MCP-compatible clients.
OpenCrab Free + from $10 per month (15,000 KRW)
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