Third-Party Notices
Last updated: 9 August 2026
Poly uses open-source software to process media in your browser. This page records what that software is, which version of it reaches you, and the licence each component is published under. It reports facts about those artifacts; it is not legal advice and it does not vary any agreement between you and Polysystems, Inc.
This page covers the media-processing pipeline. It is not yet a complete inventory of every dependency in the product, and does not claim to be.
FFmpeg — the media engine (@ffmpeg/core)
Trimming, transcoding, filtering, loudness normalisation, GIF encoding and film assembly are performed by a WebAssembly build of FFmpeg, published on npm as @ffmpeg/core@0.12.6. It is not part of the Poly application bundle. The first time you use a feature that needs it, your browser downloads it directly from the unpkg CDN at https://unpkg.com/@ffmpeg/core@0.12.6/dist/umd/ffmpeg-core.wasm, and Poly checks the downloaded bytes against a recorded SHA-256 digest before allowing them to run.
Licence
This build is published under GPL-2.0-or-later.
That is established from the binary itself rather than from package metadata. The build’s FFmpeg configuration string is compiled into the WebAssembly file, and reads:
--enable-gpl --enable-libx264 --enable-libx265 --enable-libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libopus --enable-zlib --enable-libwebp --enable-libfreetype --enable-libfribidi --enable-libass --enable-libzimg
FFmpeg built with --enable-gpl is GPL-licensed; the enabled encoders libx264 and libx265 are themselves GPL-2.0-or-later and cannot be enabled without it. The same binary embeds the GNU GeneralPublic License notice (“it under the terms of the GNU General Public License as published by…”) and contains no reference to the Lesser General Public License. These checks were run on 2026-08-09 against the artifact linked above.
A discrepancy in the published metadata
The npm registry entry for @ffmpeg/core@0.12.6 declares "license": "MIT", and the package contains no licence file. Upstream classified that field as a mistake and corrected it (issue #685, PR #686, merged 2024-03-06); version 0.12.10 carries the corrected label. The version we pin was published before that correction, so its metadata still shows the old value. The configuration strings of the two versions are identical: the label changed, the build did not.
We record this because an automated licence scan of the package metadata will report MIT for this component. That report would be wrong. The licence stated on this page is the one supported by the binary.
Enabled components
The build links the following external libraries, each under its own licence:
libx264libx265libvpxlibmp3lamelibtheoralibvorbislibopuslibwebplibfreetypelibfribidilibasslibzimgzlib
Corresponding source
The source for this build is published upstream. The WebAssembly build definition — including the configuration shown above — is at https://github.com/ffmpegwasm/ffmpeg.wasm, which builds FFmpeg from https://github.com/FFmpeg/FFmpeg. The GNU General Public License, version 2, is published by the Free Software Foundation at gnu.org/licenses/old-licenses/gpl-2.0.html.
For questions about this component, including source requests, write to legal@poly.inc.
How the binary reaches you
Stated plainly, because it is a question people ask and the answer is a matter of fact rather than of characterisation: the file is served to your browser by the unpkg CDN, from the address shown above. It is not stored in, served by, or built from Poly’s own servers or source repository. Poly’s code names the address, verifies the bytes that arrive against a recorded digest, and refuses to run anything that does not match.
FFmpeg JavaScript wrapper
The JavaScript that loads and drives the engine above is distributed separately from it, under a different licence, and is bundled with the Poly application:
@ffmpeg/ffmpeg— MIT@ffmpeg/util— MIT@ffmpeg/types— MIT
Source at https://github.com/ffmpegwasm/ffmpeg.wasm. The MIT licence on that repository covers this wrapper; it does not cover the compiled FFmpeg binary described in the previous section, which is a separately published package.
mediabunny
Media export that runs through your browser’s own WebCodecs implementation uses mediabunny 1.51.0 for demuxing and muxing, published under the MPL-2.0 and bundled with the application. Source at github.com/Vanilagy/mediabunny; the licence text is included in the distributed package. Poly does not modify it.
Corrections
If you believe anything on this page is inaccurate — a licence, a version, a source location — tell us at legal@poly.inc and we will check it against the artifact and correct the page.