Slow Down Open-source licenses
Last updated October 30, 2026
Slow Down Buddy is built on open-source software. Thank you to everyone who made these projects. The complete notices, including every copyright line and license text, are in THIRD-PARTY-NOTICES.txt.
| Component | Used for | License |
|---|---|---|
| Signalsmith Stretch 1.3.2 (Signalsmith Audio) | Slowing down and transposing | MIT |
| Emscripten runtime | Running the WebAssembly audio code | MIT |
| @wasm-audio-decoders/flac 0.2.11, opus-decoder 0.7.12, @wasm-audio-decoders/common 9.0.7, simple-yenc (Ethan Halsall) | Opening FLAC and Opus audio where the browser can't | MIT |
| libFLAC (Xiph.Org Foundation) | FLAC decoding | BSD-3-Clause |
| libopus (Xiph.Org and contributors) | Opus decoding | BSD-3-Clause |
| codec-parser 2.5.0 (Ethan Halsall) | Reading FLAC frames | LGPL-3.0-or-later (LGPL-3.0, GPL-3.0) |
| puff 2.3 (Mark Adler) | Unpacking the WebAssembly decoders | zlib-style |
| Apple Lossless (ALAC) reference decoder (Apple Inc.), ported to JavaScript | Opening Apple Lossless M4A files | Apache-2.0 |
| GoatCounter count.js (Martin Tournoij) | Anonymous visit counts | ISC |
| Demo recording: Bach, Prelude in C major, BWV 846, played by Kimiko Ishizaka | The built-in example song | CC0 1.0 (public domain) |
Source code
The FLAC and Opus decoder files on this site are the unmodified builds published on npm. Their source packages, including the LGPL-licensed codec-parser that the FLAC decoder contains, are available here:
- codec-parser-2.5.0.tgz (LGPL-3.0-or-later)
- wasm-audio-decoders-flac-0.2.11.tgz
- wasm-audio-decoders-common-9.0.7.tgz
- opus-decoder-0.7.12.tgz
- SHA-256 checksums
The FLAC decoder is a separate file (/flac-decoder.min.js) that the app loads only when it needs it, so it can be replaced with a version built from modified source. The ALAC decoder's source is m4a-decoder.js itself.