Licenses
Open-source software, models, sound samples and fonts used by Audio2MIDI.org, and the license each one is under.
Last updated: 2026-10-24
Audio2MIDI.org is built on open-source software, open models and openly licensed fonts. This page lists them with the license each one is distributed under. Versions and license identifiers were taken from each package's own package.json in our build on the date above.
Music and audio engines
These run in your browser. The heavier ones load only when a tool needs them.
| Component | Version | License | Used for |
|---|---|---|---|
| Verovio | 6.3.0 | LGPL-3.0-or-later | Engraving sheet music from MusicXML; transposing scores |
| Basic Pitch (@spotify/basic-pitch) | 1.0.1 | Apache-2.0 | Fast transcription in your browser: model weights and inference code |
| TensorFlow.js (@tensorflow/tfjs) | 3.21.0 | Apache-2.0 | Runtime that Basic Pitch runs on |
| @tonejs/midi | 2.0.28 | MIT | Reading and writing MIDI files |
| tonal | 6.5.1 | MIT | Music theory: keys, chords, scales, Camelot codes |
| pitchy | 4.1.0 | MIT | Live pitch detection for Voice to MIDI |
| Meyda | 5.6.3 | MIT | Audio features (chroma) for the key and chord finders |
| web-audio-beat-detector | 8.2.39 | MIT | Tempo detection in the BPM finder |
| smplr | 1.1.0 | MIT | Playing notes with sampled instruments |
| @breezystack/lamejs | 1.2.7 | LGPL-3.0 | MP3 encoding when you export MP3 |
About the LGPL components
Verovio and lamejs are licensed under the GNU Lesser General Public License. We use both unmodified, and each is loaded as a separate file rather than being compiled into our own code. Their complete source code is available from the projects linked above, and you can obtain it there or replace either library with a compatible version of your own. If you'd like us to send you the exact source of the versions we ship, email copyright@audio2midi.org.
About Basic Pitch
Our Fast mode uses Spotify's Basic Pitch model and code under the Apache License 2.0. The model files we serve from /models/basic-pitch/ are the unmodified files from the @spotify/basic-pitch package. Basic Pitch was introduced in A Lightweight Instrument-Agnostic Model for Polyphonic Note Transcription and Multipitch Estimation (Bittner et al., ICASSP 2022).
Sound samples
| Component | Version | License | Used for |
|---|---|---|---|
| Splendid Grand Piano | — | Public domain | Piano sound for playback and MIDI to MP3 / WAV, loaded through smplr |
Fonts
| Component | Version | License | Used for |
|---|---|---|---|
| Archivo (@fontsource-variable/archivo) | 5.3.0 | OFL-1.1 | Headings, interface and body text |
| Newsreader (@fontsource-variable/newsreader) | 5.3.0 | OFL-1.1 | Italic accent words |
| Martian Mono (@fontsource-variable/martian-mono) | 5.3.0 | OFL-1.1 | Labels and numbers |
All three fonts are licensed under the SIL Open Font License, version 1.1.
Photographs
Photographs on this site come from Unsplash and are used under the Unsplash License, which allows commercial use without attribution. We thank the photographers; the full list of photos, authors and where each one appears is kept in our project records and available on request. Demo music on this site is public domain or written for the site.
Website framework
| Component | Version | License | Used for |
|---|---|---|---|
| React | 19.2.5 | MIT | User interface |
| TanStack Router / Start | 1.170.11 / 1.168.19 | MIT | Routing and server rendering |
| TanStack Query | 5.101.0 | MIT | Data fetching |
| Tailwind CSS | 4.2.2 | MIT | Styling |
| Base UI (@base-ui/react) | 1.3.0 | MIT | Accessible UI primitives |
| Motion | 12.38.0 | MIT | Animation |
| Lucide (lucide-react) | 0.511.0 | ISC | Interface icons |
| Paraglide JS (@inlang/paraglide-js) | 2.18.2 | MIT | Translations |
| Better Auth | 1.6.2 | MIT | Sign-in and accounts |
| Drizzle ORM | 0.44.7 | Apache-2.0 | Database access |
| Zod | 4.3.6 | MIT | Input validation |
| Sonner | 2.0.7 | MIT | Notifications |
| next-themes | 0.4.6 | MIT | Light and dark theme |
Your files
The licenses above cover the software we use. They don't change the rights in the music you convert: see Copyright & DMCA for what you may upload, and our Terms of Service for how your files are handled.
Corrections
If you maintain one of these projects and something here is wrong or missing, email copyright@audio2midi.org and we'll fix it.