CaptionStack
Private by design

JSON TO SRT

JSON to SRT.

Convert JSON (.json) subtitles to SubRip (.srt) in seconds. No upload, no sign-up, nothing leaves your browser.

SRTVTTSBVLRCTTMLJSONCSVTXT
1

Choose your caption file

We’ll detect the format automatically. Drop several files to convert them all at once.

Don’t have a file handy?
2

Choose an output format

Select what you need on the other side.

100% privateYour files never leave this device.
8 formatsBuilt for the caption formats you use.
No limitsConvert as often as you need.

How to convert JSON to SRT

  1. Drop your .json file into the converter above, or click to browse. Several files at once become a ZIP.
  2. Check the quality report and fix timing or text in the editor if you need to.
  3. SRT is already selected as the output format. Click Download converted file.

Conversion happens entirely in your browser. Nothing is uploaded, no account is needed, and there is no file count limit.

About JSON (.json)

JSON is the easiest format to consume from code. CaptionStack reads an array of cue objects or an object with a cues array, accepts timestamps as milliseconds or time strings, and writes a versioned document with millisecond start and end values so you can load captions straight into a web app, database, or analytics pipeline.

About SubRip (.srt)

SRT files are plain text: a sequence number, a start and end time written as HH:MM:SS,mmm, and one or more lines of caption text. Almost every video player, editing suite, and social platform accepts SRT, which makes it the safest interchange format when you are not sure what a tool supports.

What changes when converting JSON to SRT

SRT carries timing and text only. Styling, positioning, and speaker metadata from richer formats are dropped; cue identifiers are replaced with sequence numbers.

Frequently asked questions

Is this JSON to SRT converter free?
Yes. CaptionStack is free and open source, with no limits on file count or conversions.
Are my caption files uploaded anywhere?
No. Parsing and conversion run in your browser using a local Web Worker. Your files never leave your device.
Can I edit the captions before exporting to SRT?
Yes. After import, open the editor to adjust start and end times, fix text, split, merge, or reorder cues. The quality report flags overlaps, short cues, and fast reading speeds with one-click fixes.
Can I convert many .json files to .srt at once?
Yes. Drop multiple files and download all of the results as a single ZIP archive.

Other JSON conversions

Other ways to get SRT

All caption formats