Top SEMANTIC-SEARCH GitHub Repositories & Tools (2026)

21 Lessons, Get Started Building with Generative AI

An open-source, local-first writing workspace where you can write with Claude Code and Codex, drawing on your own sources and past work.

XERJ is the new way for AI to search data. Its autoindex capability activates agents to know your data without the token waste of grep and sed. One command indexes code, docs, logs and PDFs for search, RAG, security audits and agent memory, using 40x fewer tokens than grep. Elasticsearch compatible, so existing clients just work.

A lightweight, lightning-fast, in-process vector database

grep, but the pattern is a description. Filters lines by meaning with TypeSafe's Jev decision model: ~200 ms and a thousandth of a cent per line.

The ultimate RAG for your monorepo. Query, understand, and edit multi-language codebases with the power of AI and knowledge graphs

Open-source inference server and production cluster for all the models your agent needs.

🧠 The memory that dreams — cross-session memory for DeepSeek Harness. Offline & private, auto-consolidates in its sleep (autoDream), visualized in a memory panel.

World's first open-source enterprise world model.

One Postgres for your application data, full-text search, vector retrieval, and aggregations. Home of the pg_search extension.

Graph-Native Infrastructure for Context and Accountable AI Systems

Open-source persistent memory for AI agent pipelines (LangGraph, CrewAI, AutoGen) and Claude. REST API + knowledge graph + autonomous consolidation.

Self-hosted geospatial data catalog with semantic search (pgvector), OGC/STAC APIs, and map builder. Built on FastAPI, PostGIS, React, and MapLibre.

Open-source, self-hosted enterprise & site search server built on OpenSearch. Crawls web / file / DB / cloud sources, 20+ languages, REST API, and AI/RAG & semantic search. Apache-2.0.

Find code by asking what it does. A CLI for coding agents that uses Jev to discover relevant files and source context.

Structural code intelligence for AI agents — semantic search, knowledge graphs, and a built-in MCP server in one Rust binary. Give Claude, Cursor, and any MCP client a deep understanding of your codebase.

Open-source cognitive coprocessor with active memory for AI agents — persistent recall, semantic search, overnight dreaming, verified facts, encrypted USB sync. MCP server; works with Claude, ChatGPT, and any local LLM. Built by one maker and his agents.

MCP server that lets Claude Code and other AI agents read and search large PDFs, one file or a whole folder: agentic RAG with hybrid semantic + keyword search, selective page reads, tables, images, OCR, chart data, and multi-column/CJK layouts.

The EMBL-EBI Ontology Lookup Service (OLS)

A free, open-source Obsidian plugin that makes your vault smarter: better search, an interactive knowledge graph, and an AI assistant that knows your notes.