Faiss

a library for efficient similarity search and clustering of dense vectors
contains algorithms that search in sets of vectors of any size, up to ones that possibly do not fit in RAM
contains supporting code for evaluation and parameter tuning.
written in C++ with complete wrappers for Python
Some of the most useful algorithms are implemented on the GPU
developed by Facebook

pip install faiss-cpu
pip install faiss-gpu

index = faiss.IndexFlatL2(d)   # build the index
print(index.is_trained)
index.add(xb)                  # add vectors to the index