pylsl is a Python binding for the Lab Streaming Layer (LSL), a real-time network protocol for exchanging time-series data, primarily used in neuroscience and biomedical research. The library provides a clean, ctypes-based interface to the native liblsl C library, exposing classes for stream declaration (StreamInfo), data output (StreamOutlet), data input (StreamInlet), and network discovery (resolve_streams, ContinuousResolver). The codebase is well-structured with thorough error handling, graceful degradation for older liblsl versions, and comprehensive test coverage. It includes a micro-benchmarking suite for measuring ctypes call overhead and data conversion costs. The library is actively maintained, with CI/CD pipelines, platform-specific wheels bundling liblsl, and support for Python 3.10–3.13.