lamejs

lamejs is a pure JavaScript MP3 encoder library, initially a rewrite of jump3r-code which itself was based on libmp3lame. It enables client-side and server-side (Node.js) encoding of raw PCM audio data (specifically Int16Array samples) into MP3 format. The project highlights its performance, claiming to be significantly faster than real-time on various machines and environments (browser and Node.js). The current stable version is 1.2.1, released after a considerable hiatus, primarily to address a TypeScript compatibility issue. Its release cadence is slow, suggesting a maintenance rather than actively developed status. Key differentiators include its pure JavaScript implementation, making it suitable for browser-based audio processing without WASM, and its reported high encoding speed. It's particularly useful for scenarios requiring on-the-fly MP3 generation from Web Audio API outputs or other PCM sources.