Open Source Licenses

MKV to MP4 converts videos inside your browser with FFmpeg, compiled to WebAssembly by the ffmpeg.wasm project. We did not write the converter and we have not changed it. This page lists what it is made of, the licenses it comes under, and where to get the source code.

What runs in your browser

When you convert a file, your browser downloads these unmodified npm packages and runs them on your device:

• @ffmpeg/ffmpeg 0.12.15 and @ffmpeg/util 0.12.2, the JavaScript wrapper. License: MIT.
• @ffmpeg/core 0.12.10, FFmpeg n5.1.4 built as WebAssembly, served by the jsDelivr CDN. License: GNU General Public License, version 2 or later, because it is built with --enable-gpl and includes GPL libraries.

Libraries inside @ffmpeg/core

• FFmpeg n5.1.4: LGPL-2.1-or-later, GPL-2.0-or-later as built here
• x264 (H.264 encoder): GPL-2.0-or-later
• x265 (HEVC encoder): GPL-2.0-or-later
• libvpx (VP8 / VP9): BSD-3-Clause
• LAME (MP3): LGPL-2.0-or-later
• libogg, libvorbis, libtheora: BSD-3-Clause
• Opus: BSD-3-Clause
• zlib: zlib License
• libwebp: BSD-3-Clause
• FreeType: FreeType License (FTL) or GPL-2.0
• FriBidi: LGPL-2.1-or-later
• HarfBuzz: MIT ("Old MIT")
• libass: ISC
• zimg: WTFPL

Source code

The exact source of the build we use, including the Dockerfile and the build scripts that pin every library version, is the ffmpeg.wasm v12.15 release, which publishes @ffmpeg/core 0.12.10. FFmpeg itself is the n5.1.4 tag.

If any of those links stops working, write to support@mkv-to-mp4.org and we will send you a complete copy of the corresponding source code, at no charge beyond the cost of delivering it. This offer is valid for three years from the last time we served the software.

Your rights

The GPL lets you run, study, share and change this software. It comes with no warranty. The full terms are in the GNU General Public License, version 2. The rest of MKV to MP4, the website around the converter, is our own work and is not covered by these licenses.