Convert SRT to WebVTT and back

How Subtitle Converter works

The arithmetic is a multiplication against a fixed factor table that ships with the page. A conversion needs no server because the factor never changes — only the number you gave it does. That also means the answer is reproducible: the same input gives the same output offline, in five years, on a plane.

That is the whole architecture: static files, one script, no upload endpoint to leak or log. Close the tab and the work is gone.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions