What actually differs between SRT and WebVTT?

Structurally very little. WebVTT requires a WEBVTT header line at the top and uses a dot before the milliseconds (00:00:01.000) where SubRip uses a comma (00:00:01,000). The converter handles both changes and leaves the cue text intact.

Do inline formatting tags carry over?

Yes. Tags like the italic and bold tags are valid in both formats, so they pass through unchanged. SubRip positioning coordinates that WebVTT does not support are dropped from the timing line.

Why does WebVTT need a header?

Browsers refuse to load a track that doesn't begin with the literal text WEBVTT. The converter always inserts it as the first line so the file works with the HTML5 track element straight away.

Does it keep the cue numbers?

WebVTT allows an optional identifier line before each cue, so the numeric index from the SRT is preserved as that identifier. It is harmless and can help with debugging; players ignore it.

Are my subtitles uploaded?

No. The conversion runs entirely in your browser. Your subtitle file is never sent to a server, which keeps unreleased or private captions on your device.

SRT to WebVTT Converter

WebVTT is the captioning format that HTML5 video understands through the <track> element, while SubRip (.srt) is the format most subtitle editors and download sites produce. The two are nearly identical, which is why converting between them is fast and lossless. This tool turns an .srt into a browser-ready .vtt.

How it works

The converter normalises line endings, strips a leading byte-order mark if present, and walks the file cue by cue. For each cue it:

Reads the optional index — the bare number above the timestamps. WebVTT allows an identifier line, so this is kept.
Rewrites the timing line. A SubRip timing line such as 00:00:01,000 --> 00:00:04,000 becomes 00:00:01.000 --> 00:00:04.000. The only change is the comma before the milliseconds turning into a dot. Timestamps with a single-digit hour are padded to two digits, and any SubRip positioning coordinates after the times — which WebVTT doesn’t accept in that form — are removed.
Copies the text lines verbatim until the blank line that ends the cue.

Finally it prepends the mandatory WEBVTT header. Without that header browsers reject the track entirely.

Inline tags

Basic styling tags such as <i> (italic) and <b> (bold) are valid in both SubRip and WebVTT, so they pass straight through. If your captions rely on them, the formatting survives the conversion.

Example

A SubRip cue:

1
00:00:01,000 --> 00:00:04,000
Welcome to the demo subtitle.

becomes, after the WEBVTT header:

WEBVTT

1
00:00:01.000 --> 00:00:04.000
Welcome to the demo subtitle.

You can then reference the file from a video element:

<track kind="subtitles" src="subtitles.vtt" srclang="en" label="English">

Everything runs in your browser — your subtitles are never uploaded.