SPANN

Microsoft's cloud-based search service with integrated vector search, hybrid search, and semantic ranking capabilities. Provides both traditional full-text search and modern vector-based semantic search with built-in AI enrichment.

Parameterless and Universal Fast Finding of Nearest Neighbors - an LSH-based library for approximate nearest neighbor search with probabilistic guarantees. Features a parameterless design requiring only memory budget and result quality specifications.

A C++ library for approximate nearest neighbor searching in arbitrarily high dimensions, developed by David Mount and Sunil Arya at the University of Maryland. Provides data structures and algorithms for both exact and approximate nearest neighbor searching.

A C++ library for performing fast approximate nearest neighbor searches in high dimensional spaces. Contains multiple ANN algorithms and automatic algorithm selection based on dataset characteristics.

Scalable Nearest Neighbors library by Google Research that provides efficient vector similarity search at scale. Uses anisotropic vector quantization and advanced compression techniques to handle twice as many queries per second compared to alternatives.

Fast Library for Approximate Nearest Neighbors containing a collection of algorithms optimized for nearest neighbor search in high dimensional spaces with automatic algorithm and parameter selection.