Jubler

Jubler is a free, open‑source subtitle editor that lets users create, modify, and convert text‑based subtitle files. It supports more than twenty subtitle formats such as SRT, ASS/SSA, WebVTT, MicroDVD, TTML and YouTube subtitles, and provides tools for authoring new subtitles or refining existing ones with video preview, quality validation and format‑specific styling.

The editor integrates with FFmpeg for frame‑accurate preview and audio waveform display, and can use MPlayer for real‑time video playback while editing. An interactive timeline allows draggable subtitle blocks, two‑point synchronization, and features like time shifting, frame‑rate conversion, split/join operations, spell checking, and regex‑based find‑and‑replace. Quality checks follow configurable rules and TED guidelines, and a translation mode offers Azure Translator support.

Jubler runs on macOS, Windows and Linux, is written in Java 8 for cross‑platform compatibility, and includes command‑line utilities for batch processing. It is released under the GNU AGPL‑3.0 license.