Subtitle validator

01

SRT or WebVTT?

Both are plain-text caption files: a number or an ID, a timing line, then the text. SRT writes times as 00:00:01,000 with a comma, WebVTT as 00:00:01.000 with a period and needs WEBVTT on its first line. YouTube, Facebook and LinkedIn accept SRT; web players and many editors prefer VTT. The converter turns one into the other and keeps WebVTT cue settings when you stay in VTT.

02

Errors vs. readability

Errors break the file: an unreadable timing line, a caption that ends before it starts, captions out of order or overlapping. A player may skip them or refuse the file. The Fix button sorts the captions, removes empty and backwards ones and trims overlaps, without touching your text.

Readability notes are about the viewer: lines over 42 characters, more than 2 lines, more than 20 characters per second, or captions shorter than about 0.8 s or longer than 7 s. These come from Netflix's public timed-text style guide, a widely used quality bar, not a rule of the social platforms, so treat them as advice.

03

Shifting captions

If you trimmed the first seconds of a video after exporting its captions, every caption is now late by the same amount. Enter the difference as a negative number of seconds and download again. Captions never move before 0:00.