Leiden is a general algorithm for methods of community detection in large networks. This package implements the Leiden algorithm in C++ and exposes it to Python. Besides the relative flexibility of the implementation, it also scales well, and can be run on graphs of millions of nodes (as long as they can fit in memory). The core function is find_partition which finds the optimal partition using the Leiden algorithm, which is an extension of the Louvain algorithm, for a number of different methods.