Subler

Subler is a free, open‑source application for macOS that provides an easy interface for creating and editing MP4 files. It is written mainly in Ruby using the Cocoa API, and the user interface is developed with Apple's Interface Builder. The program is distributed under the MIT license and can be downloaded from the Subler project site or through Homebrew on macOS.

The primary function of Subler is to mux individual media components, such as video, audio, and text tracks, into a single MP4 container. Users can import QuickTime or other compatible files and then add subtitles, chapter information, and closed caption files. Subtitles can be added in formats such as SRT, WebVTT, or Timed Text, and the application offers basic editing tools for timing and styling. Subler also supports adding metadata tags, including titles, artwork, and iTunes Useful Metadata like region and call sign information, making it popular for creating media for iTunes and other Apple platforms.

Subler contains additional features for advanced users. It allows drag‑and‑drop of files into the interface and supports quick preview of the final movie. The application can also legalize DVD-encoded video for use on Apple devices. Although the original project stopped receiving updates as of 2012, the source code remains available and has been forked by several developers who continue to provide updates and bug fixes for newer macOS releases.

Because Subler operates only on macOS, it is most often used by video enthusiasts, podcasters, and independent filmmakers who need a straightforward tool to combine multiple tracks into a single MP4 without engaging with command‑line FFmpeg scripts. The application remains a popular choice for people who prefer a graphical interface but need the flexibility of a fully open‑source solution.