TurboVec

Library for efficient similarity search and clustering of dense vectors at billion-scale.

FAISS is Meta AI Research's open-source library for efficient similarity search and clustering of dense vectors. It implements approximate nearest-neighbor algorithms designed to scale to billions of vectors, with optimized indexes that fit in RAM and GPU acceleration for the largest workloads. Engineering teams use FAISS as the retrieval primitive underneath custom RAG pipelines, recommendation systems, and large-scale embedding search infrastructure.

Fast embeddable vector search engine

USearch is a high-performance vector search engine implementing HNSW algorithms for approximate nearest neighbor queries across C++, Python, JavaScript, Rust, Java, Go, and more. It supports user-defined distance metrics, memory-mapped persistence for datasets larger than RAM, and filtered search with predicates. Used by YugabyteDB and ScyllaDB as their production vector indexing backend.

Header-only C++ implementation of HNSW for fast approximate nearest-neighbor search.

hnswlib is a header-only C++ library implementing the Hierarchical Navigable Small World (HNSW) graph algorithm for approximate nearest-neighbor search, with Python bindings and a tiny dependency footprint. Originally developed by the nmslib team, it has become the default HNSW implementation embedded inside many vector databases and search products. Engineers use it directly when they want HNSW retrieval without pulling in a heavyweight vector DB.

Vector search extension for SQLite that runs anywhere

sqlite-vec is a lightweight vector search extension for SQLite written in pure C with zero dependencies. It brings nearest-neighbor search capabilities directly into SQLite databases, enabling AI applications to store and query embeddings without running a separate vector database. The extension works everywhere SQLite runs including Linux, macOS, Windows, WebAssembly in browsers, and even Raspberry Pi devices. Sponsored by Mozilla Builders, Fly.io, and Turso.

In-process vector database — the SQLite of vector DBs

Zvec is an open-source in-process vector database from Alibaba designed as the SQLite of vector search. It runs as an embedded library directly inside applications without requiring external servers, delivering 8,000+ QPS with high recall rates. Zvec supports dense and sparse embeddings, multi-vector queries, and combined semantic plus structured filtering. Built on Alibaba's proven Proxima engine, it provides a lightweight alternative to server-based vector databases for local AI workflows.

Microsoft's distributed approximate nearest neighbor search library and billion-scale vector engine

Microsoft's distributed approximate nearest neighbor search library and online vector serving engine, utilizing space-partition trees and relative neighborhood graphs for billion-scale semantic retrieval.

High-performance on-device object and vector database for mobile and edge AI

High-performance on-device object and vector database designed for mobile, IoT, and edge applications, providing sub-millisecond local HNSW vector search and optional cloud-optional data synchronization.

High-performance vector database written in Rust for similarity search at scale.

Qdrant is a high-performance vector similarity search engine and database written in Rust. Designed for production-grade AI applications with advanced filtering, payload indexing, and distributed deployment. Supports billion-scale vector collections with sub-second query times. Popular choice for RAG, recommendation systems, and anomaly detection.

Fully managed vector database built for AI applications at production scale.

Pinecone is a leading managed vector database designed for high-performance similarity search at scale. Purpose-built for AI applications including RAG, recommendation systems, and semantic search. Offers managed serverless infrastructure with automatic scaling, filtering, hybrid retrieval, and namespacing. No infrastructure management required.

High-performance OLTP graph-vector database in Rust built on object storage for AI memory

HelixDB is an open-source, unified graph-vector database engineered in Rust that merges relational, graph, and vector workloads into a single OLTP engine, using LMDB local caching and S3 object storage for scalable agent memory.

Embedded vector database for multimodal AI with petabyte scale

LanceDB is an open-source embedded vector database built on the Lance columnar format for multimodal AI. It delivers near in-memory performance from disk with zero-copy architecture, supporting vector search, full-text search, and SQL. Native SDKs for Python, TypeScript, and Rust integrate with LangChain, LlamaIndex, and DuckDB. Backed by a $30M Series A, used by Harvey AI and Runway, with 18,000+ GitHub stars.