Free browser tool

Free SRT / VTT checker, timing shift and converter

Check a subtitle file, move every cue by the same number of seconds, and export SRT, VTT or plain text.

1. Paste SRT/WebVTT or select a UTF-8 file up to 2 MiB.
2. Use 0 to validate only; +1.5 makes cues appear later, -1.5 earlier.
3. Review the report, download your chosen format, and check it with the video.

What the report means

Errors block all exports: malformed timestamps, missing text, a cue ending before it starts, or a shift below zero. Overlaps and out-of-order cues are warnings, because they may be intentional. Cue order and wording are preserved; SRT cue numbers are normalized.

Readability hints flag more than two lines, lines over 42 characters, or more than 20 characters per second. These are editorial heuristics used by this tool, not a legal standard or a platform compliance check. Watch the video to decide what needs editing.

Format limits

Accepts UTF-8, an optional BOM, and LF or CRLF line endings. WebVTT needs a WEBVTT header followed by a blank line. WebVTT cue placement settings, STYLE/REGION blocks, header metadata and inline timestamps are rejected to avoid silent loss or an incomplete shift. NOTE comments are omitted with a warning. Inline text markup is preserved as written; check player compatibility. TXT removes timing and numbering, but does not strip inline text markup.

A constant shift cannot repair drift or an edited video. This tool does not listen to audio, check translation quality, or create subtitles from a recording.