Caption files and the metadata that travels with video. The subtitle work is the substantial part: converting between the two formats that matter, diagnosing whether a file needs a constant shift or a frame-rate scale, merging two halves of a film and splitting one file in two.
This is also the section where the site’s network posture stops being uniform, and it is stated plainly rather than buried. The Subtitle Toolkit runs entirely on your device. The other two tools here contact the network by design, because reaching a named host is what they are for, and each announces every request in its interface before making it.
What people use these for
Converting an SRT file to WebVTT so a track element in a browser will display it.
Fixing subtitles that drift further out of sync as the film plays.
Shifting a whole caption file by a measured number of milliseconds.
Merging the two halves of a film that was subtitled in parts.
Stripping formatting tags out of a caption file while keeping the line breaks.
Pulling the published thumbnail sizes and public title for a video link.
Privacy in this section
Subtitle files often contain unreleased dialogue, so the Subtitle Toolkit has no server component at all. The other two tools in this section do make network requests as part of their normal operation; their own pages state exactly which hosts they contact and when.