How are the two tracks combined?

Every cue from both files is parsed into a start time, end time and text, then all cues are sorted together by start time and written out as one file. Where cues from each track sit close together, they appear back to back in the merged timeline.

What is the {B} prefix for?

When the prefix option is on, every cue that came from Track B is labelled with {B} at the start of its text. This makes it easy to see which line came from which source — useful when merging, for example, dialogue subtitles with director commentary.

Will both lines show on screen at the same time?

Not necessarily. Standard SRT and VTT players show whichever cue is active for the current time. If two cues overlap in time, most players stack them; if they do not overlap, they appear in sequence. This tool preserves each cue's original timing exactly.

Can I merge an SRT and a VTT together?

Yes. The tool reads both SubRip and WebVTT input regardless of which file is Track A or Track B, and you choose a single output format for the combined result.

Are my subtitle files uploaded?

No. Both files are parsed, sorted and merged in your browser using JavaScript. Nothing is sent to a server, so even private or unreleased subtitle tracks stay on your device.

Subtitle File Merger

The subtitle file merger combines two caption tracks into a single timeline. It is built for cases where you want two streams of text in one file — a foreign-language track plus a hearing-impaired track, dialogue plus director commentary, or original captions plus translated notes. Paste or load Track A and Track B, and the tool weaves their cues together in timestamp order.

How it works

Each track is parsed independently into a list of cues, where every cue has a start time, an end time and its text. SubRip and WebVTT inputs are both accepted — the parser skips the WebVTT header, NOTE and STYLE blocks and any numeric index lines, and reads the start --\> end timing line followed by the caption text. Optionally, each Track B cue is prefixed with a \{B\} label so its source is obvious.

The cues from both tracks are then merged into one array and sorted by start time (ties broken by end time), so the combined file reads chronologically from beginning to end. Finally the merged cues are serialised to your chosen format: SubRip numbers each cue and uses comma decimals, while WebVTT writes the WEBVTT header and dot decimals.

Example and notes

If Track A holds the English dialogue and Track B holds commentary, a merged file might read:

1
00:00:01,000 --> 00:00:03,000
Hello there.

2
00:00:02,000 --> 00:00:04,000
{B} [Director commentary]

Note that the original timings are kept exactly, so overlapping cues remain overlapping. If you need the two streams visually separated on screen, keep the \{B\} prefix on so each source is labelled. Everything runs locally — neither file leaves your browser.