This is the core implementation of UMAP (Uniform Manifold Approximation and Projection), a scikit-learn-compatible library for non-linear dimensionality reduction. The repository provides a well-structured modular architecture with core classes UMAP, ParametricUMAP (TensorFlow-based), and AlignedUMAP for jointly embedding multiple related datasets. It features a rich set of numba-accelerated distance functions, sparse matrix support, spectral initialization, and a sophisticated optimization engine. Although primarily a library, the repo includes extensive Jupyter notebooks and documentation demonstrating research workflows (parametric UMAP with reconstruction, hyperparameter animation, global loss tuning). The codebase is actively maintained, with ongoing work to remove deprecated patterns such as fastmath, but retains some technical debt (unresolved FIXMEs, sparse test coverage in some areas, and dependency on older scikit-learn APIs). Overall, it is a high-quality, reusable library with clear separation of concerns, making it suitable for integration into data science pipelines and for study of manifold learning techniques.