You generated JSON captions — an array of cue objects — and now you need a real SRT file. The JSON to SRT Converter rebuilds standard SubRip text from your data.
Point it at an array of cues with start, end and text. Timestamps may be timecode strings (HH:MM:SS,mmm or with a period) or numbers of seconds; the converter normalizes everything to HH:MM:SS,mmm, inserts the --> arrow, numbers the cues (using your index when present), and joins them with blank lines. Multi-line text in a string is preserved, so you get a faithful SRT in one click.