Open source

Tonify writes MP3 with LAME (libmp3lame 3.100), licensed under the LGPL. LAME is linked as a dynamic framework, so it can be replaced with your own build, as the licence asks. The wrapper is a fork of hidden-spectrum/SwiftLAME via tcwalther. Licence texts are in the app under Settings › About › Open-source licenses, and our copy of the source is published so what we ship is what you can inspect. Everything else in the audio path is Apple's AVFoundation.

• lame.sourceforge.io
• ffmpeg.org
• github.com/yaysoft-ltd/swiftlame

Last updated: 2026-10-24