Library / SDK
Retrieval & Memory
hnswlib
1Fast 2approximate 3nearest-neighbor 4search 5in 6C++
the six Ws · specification
W1
Who
Maintained by the nmslib authors.
W2
What
A header-only library for fast HNSW vector search.
W3
Where
An embedded library in C++ and Python.
W4
When
When you need in-process approximate nearest-neighbor search.
W5
Why
The reference HNSW implementation many tools build on.
W6
With
Your vectors and a C++ or Python binding.
W7
Watch
Community and academic-maintained; open-source (Apache-2.0), library only. Runs embedded in your process; data stays local.