Legal

Open-source software

Anjin Ltd, trading as Anjin Media · Company no. 16378036 · Last updated 23 September 2026

The free tools under /tools that convert, edit and reformat video, audio and GIF files do that work entirely in your browser. This page names the open-source libraries that do it, what each one does, and its licence.

1 What runs in your browser

The tools that convert between MP4, MOV, MKV, WebM, MP3 and GIF, the video compressor, the quick video edits, the 16:9 to 9:16 converter, the audiogram maker and the safe zone checker (for a video) load a small media engine into your browser the first time you use one of them. That engine is built on five open-source libraries, together with the audio and video codecs your browser already provides. The one extra download is the MP3 encoder: if your browser cannot make MP3 itself, that code is downloaded from this site the first time the video-to-MP3 tool needs it. The file you give a tool is read, converted and offered back to you by code running locally; your file is never sent anywhere, which is what Mediabunny and the packages alongside it make possible.

2 The libraries

Each licence and version below was read from the installed package's own package.json and LICENSE file (not from an npm listing or the package's website) on 22 September 2026, and for fflate on 23 September 2026.

LIBRARYWHAT IT DOES · LICENCE

Mediabunnyv1.59.0: Reads, probes and re-packages video and audio files directly in the browser. It is what the MOV, MKV and WebM to MP4 converters, the video compressor and the video-to-MP3 and video-to-GIF tools actually run, and it encodes the video in the GIF to MP4 tool. The quick video edits, the 16:9 to 9:16 converter and the audiogram maker are built on it too, and the safe zone checker uses it to read a frame from a video.Licence: MPL-2.0 · Source: github.com/Vanilagy/mediabunny/tree/v1.59.0
@mediabunny/mp3-encoderv1.59.0: Gives Mediabunny an MP3 encoder for browsers whose own WebCodecs implementation cannot produce one, used by the video-to-MP3 tool.Licence: MPL-2.0 wrapper · Source: github.com/Vanilagy/mediabunny/tree/v1.59.0/packages/mp3-encoderThis wrapper's own code is MPL-2.0, the same licence as Mediabunny. It works by loading a WebAssembly build of the LAME MP3 encoder (next row), which LAME licenses separately under the LGPL.
LAME 3.100 (inside @mediabunny/mp3-encoder): The actual MP3 encoding math the wrapper above calls: an unmodified build of LAME 3.100, compiled to WebAssembly with its decoder and command-line frontend disabled, so it only ever encodes.Licence: GNU LGPL version 2 or later · Source: sourceforge.net/projects/lame/files/lame/3.100/
The WebAssembly build's own source, the bridge code that calls LAME (lame-bridge.c) and the exact build commands used to produce it: github.com/Vanilagy/mediabunny/tree/v1.59.0/packages/mp3-encoder (contains lame-bridge.c, the prebuilt libmp3lame.a and the README's build commands).
You can rebuild the encoder from these sources and substitute your own build, for example by overriding the script in your browser's developer tools.
On request, we will supply the LAME 3.100 source and the build files: write to legal@anjin.media.
LAME's own licence notice asks anyone using it to credit the project: this build uses LAME, the open-source MP3 encoder.
gifencv1.0.3: Builds the animated GIF a browser encodes for the video-to-GIF tool: colour quantisation and the GIF encoder itself.Licence: MIT · Source: github.com/mattdesl/gifenc
gifuct-jsv2.1.2: Decodes an existing GIF's frames back out again, which the GIF-to-MP4 tool needs before it can re-encode them as video.Licence: MIT · Source: github.com/matt-way/gifuct-js
fflatev0.8.3: Packs several finished files into one ZIP download, for the video splitter's parts and the frame extractor's images. The files are stored in the ZIP as they are, not compressed again.Licence: MIT · Source: github.com/101arrowz/fflate

3 The MIT licence text

gifenc, gifuct-js and fflate are all released under the MIT licence, with the same licence body and three different copyright holders. Rather than print the same text three times, here it is once, with all three copyright lines:

The MIT License (MIT)

Copyright (c) 2017 Matt DesLauriers (gifenc)
Copyright (c) 2015 Matt Way (gifuct-js)
Copyright (c) 2026 Arjun Barrett (fflate)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

4 Questions about this list

If a licence obligation needs something from us that is not on this page (written attribution in a specific form, a copy of source code, anything else a licence entitles you to), write to legal@anjin.media.

Anjin Ltd is a company registered in England and Wales (no. 16378036). Registered office: 213 Station Road, Stechford, Birmingham, England, B33 8BB. VAT registration no. GB 520 1604 48. Registered with the Information Commissioner's Office, no. ZC154847.

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