.vtt File Extension

What kind of file is a .vtt?

A .vtt file uses the Web Video Text Tracks format, usually called WebVTT. It stores timed text cues that accompany audio or video. Most files contain subtitles or captions, but WebVTT can also represent descriptions, chapter markers, and time-aligned metadata.¹

WebVTT uses the registered text/vtt MIME type and UTF-8 text. A conforming file begins with WEBVTT, optionally after the UTF-8 byte-order mark. That signature is a stronger identification clue than the filename alone.²

Each basic cue has a start time, an end time, and a text payload. The format can also include cue identifiers, placement settings, voice and language spans, and NOTE, STYLE, or REGION blocks.¹

How do I open a .vtt on my computer?

Open a VTT file in any UTF-8 text or code editor on Windows, macOS, Linux, or ChromeOS when you want to inspect or change its cues. A dedicated caption editor is better for waveform-based timing, line-length checks, and testing placement against the related media.

Modern browsers use WebVTT with the HTML <track> element. The element associates an external text track with <video> or <audio> and declares whether it provides subtitles, captions, descriptions, chapters, or metadata.³ Media players such as VLC can also load an external VTT track alongside a compatible video.

Opening a standalone VTT URL in a browser may display raw text or download it. To see captions at the right moments, attach the file to its matching media and test the complete playback experience.

Poly support for .vtt

Poly opens VTT files in a code-friendly text editor, indexes their readable contents for exact and semantic search, and makes that text available to the Poly agent. You can find a file by spoken wording, a speaker label, or a timestamp, then ask the agent to summarize the transcript or review cue timing and wording.

The preview shows WebVTT source rather than synchronized captions over a video. Poly does not automatically pair a standalone VTT file with its related media. Keeping descriptive filenames for both files makes the relationship easier to recognize.

History of .vtt

WebVTT grew from the web platform's work on timed text tracks, with the community-created SubRip format as an important starting point. W3C published its first standalone WebVTT working draft on November 13, 2014.⁴ The specification remains on the W3C standards track and is designed around HTML media's <track> element.¹

The .vtt suffix became the registered filename convention for WebVTT. IANA registered text/vtt in 2019 and specifies vtt as its extension. The registration also defines the WEBVTT signature and requires UTF-8 encoding.²

Working with .vtt and alternatives

When converting SRT to VTT, add the required header, change comma-based milliseconds such as 00:00:02,500 to period-based WebVTT timestamps, and validate cue timing. Converting VTT in the other direction may discard regions, positioning, styling, or metadata.

Always review captions against the media. A syntactically valid file can still have inaccurate wording, missing speaker labels, distracting line breaks, or cues that appear too quickly. VTT files can also expose complete dialogue or private events, so review them separately before publishing.