About

Cuelatch does one thing: it corrects the timing of a subtitle file. It is run by Cuelatch Ltd.

Why it exists

There is no shortage of tools that shift subtitle timestamps. Most of them treat a subtitle file as text to be parsed, rebuilt and written back out, which is where the damage happens: styling is dropped, line endings flip, cue numbering is rewritten, non-UTF-8 files come back as mojibake, and some tools will happily emit a negative timestamp that no player can read.

That is the problem worth solving. Shifting numbers is easy. Shifting them while guaranteeing that everything else in the file survives is the part that takes care.

How it works

The engine does not parse a subtitle file into a model and write a new one out. It locates the character spans holding timestamps and rewrites only those, leaving every other byte where it was.

That distinction is the whole design. Because anything not explicitly located cannot be altered, preservation is structural rather than a rule each format handler has to remember. ASS style blocks, embedded fonts, positioning and karaoke tags, WebVTT cue settings and comments, byte order marks, CRLF line endings and original cue numbering all survive because nothing ever touches them.

The guarantees are covered by an automated test suite rather than asserted here. Among them: a shift of zero returns the input byte for byte; a negative timestamp is never written; each format rounds to its own real precision, so milliseconds for SRT and WebVTT, centiseconds for ASS and LRC, whole frames for MicroDVD; and a malformed cue is passed through untouched and reported rather than silently dropped.

Everything runs on your machine

There is no backend. Files are read, corrected and saved by your own browser, and nothing is uploaded — including the video or audio used by automatic detection, which decodes locally to find the offset. This is not a promise about how data is handled; there is simply nowhere for a file to go. Theprivacy page sets out what that means precisely.

What it will not become

Scope is a feature. Cuelatch is not a subtitle editor, and will not gain per-line text editing, styling controls or translation. There is no transcription and no account system. It will not grow into a directory of loosely related converters, because every tool that has done so got worse at the thing it was originally good at.

The written guides exist to explain problems, not to fill a content calendar. If a page here does not answer the question in its title, it has failed and should be fixed.

Corrections

If something on this site is wrong — a frame-rate figure, a keyboard shortcut, a claim about how another player behaves — that is worth reporting and will be corrected. Accuracy is the only reason to read any of it.Get in touch.