JSON to VTT Subtitle Converter

Quickly convert Structured JSON subtitles to WebVTT locally in your browser. Timelines and subtitle content are never uploaded.

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What happens when converting JSON to VTT?

Structured JSON content is parsed into a unified millisecond timeline before being exported as WebVTT. Valid timing and subtitle text are preserved.

WebVTT output uses dot-separated millisecond timestamps and includes the WEBVTT file header.

JSON input supports an array of subtitles or an object containing a cues or subtitles array.

Format overview

About JSON and VTT subtitle formats

Learn what each file format is, how it is structured, where it is commonly used, and what to consider during conversion.

Source file format

JSON · Structured JSON

JSON, or JavaScript Object Notation, is a structured data-interchange format rather than one industry-standard subtitle specification. Explicit fields can represent timing, text, and extensible metadata.

File structure: This tool uses a JSON object containing a cues array. Each cue has start_ms, end_ms, and text fields representing the start time, end time, and subtitle text.
Common uses: JSON is useful for subtitle software development, API exchange, batch processing, data analysis, automation, and preserving structured subtitle data for later programmatic or AI processing.
Conversion notes: Subtitle JSON schemas vary between applications. This tool can read subtitle arrays and objects containing cues or subtitles arrays, and it exports a consistent cues structure.

Target file format

VTT · WebVTT

VTT, or WebVTT, is a timed-text format designed for web video. HTML5 video elements can use it through track elements for subtitles, captions, chapters, and other synchronized text.

File structure: A WebVTT file normally begins with a WEBVTT header and uses a dot as the millisecond separator. It may also contain cue identifiers, positioning settings, comments, and metadata.
Common uses: VTT is commonly used by web players, online courses, recorded streams, accessible closed captions, and videos that need subtitles displayed directly by modern browsers.
Conversion notes: VTT supports richer web-caption features than SRT. Cue positioning, voice tags, chapters, and some metadata may not survive conversion to simpler formats.