JSON to ASS Subtitle Converter

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

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What happens when converting JSON to ASS?

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

ASS output uses a compatible ASS v4+ default style while preserving subtitle text and timing.

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

Format overview

About JSON and ASS 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

ASS · Advanced SubStation Alpha

ASS, or Advanced SubStation Alpha, is an enhanced successor to SSA. It can precisely control subtitle fonts, colors, positions, animation, and karaoke effects.

File structure: ASS files are organized into sections such as Script Info, V4+ Styles, and Events. Subtitle cues are usually stored as Dialogue lines that reference predefined styles.
Common uses: ASS is commonly used for anime subtitles, visual subtitle effects, complex typesetting, karaoke, and video workflows that require precise presentation control.
Conversion notes: ASS can express much more styling than SRT, LRC, or TXT. When converting to a simpler format, this tool preserves visible text and timing but not complex styling, positioning, or animation.