Subtitle checker and fixer for SRT, VTT and ASS

Subtitles that pass QC the first time.

Drop in an SRT, VTT or ASS file. Subtidy rebalances long lines, gives fast cues room to breathe, closes overlaps and checks every caption against the frame.

Files are processed in your browser and never uploaded. Exports open in Premiere Pro, DaVinci Resolve, Final Cut Pro and YouTube.

Rebalanced, not just wrapped

Line breaks land on natural pauses. Cues that need too many lines are split, with their timing shared out by length.

Timing people can read

Fast cues borrow time from the gaps around them. Overlaps close, and every cue keeps a clean gap before the next.

Checked against the frame

Preview any cue in 16:9 or 9:16 and see when a line runs past title safe or under the app buttons on Reels and TikTok.

Private by default

Everything runs on your machine. Client subtitles never touch a server, so there is nothing to sign before you use it.

Workspace

Drop subtitle files anywhere on the page. Change a rule and every file updates instantly.

Drop SRT, VTT or ASS files

Add a whole series at once. Each file gets its own report, and you can download them together.

Or paste subtitle text

Pricing

Free handles one file at a time. Pro is for people who subtitle for a living.

Free

$0

No account needed.

  • Every automatic fix: line balancing, splitting and timing
  • Streaming, broadcast and social presets
  • 16:9 title safe preview and full QC report
  • SRT export
  • One file at a time
Use it free

Pro

$39/year

Works out to $3.25 a month.

  • Everything in Free
  • Batch a whole series and download it as one zip
  • Custom limits for any client or broadcaster spec
  • 9:16 check against Reels and TikTok overlays
  • WebVTT, ASS and transcript export
  • Frame rate conversion and timing shift

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Questions

What editors ask before they drop in a file.

What is Subtidy?

Subtidy is a subtitle checker and fixer that runs in your web browser. It checks SRT, WebVTT and ASS files against the rules you pick, fixes what it can automatically, and shows a before and after quality report for every file.

Are my subtitle files uploaded?

No. Files are read and processed inside your browser and are never sent to a server. You do not need an account to use the free version.

What does it check?

Every cue is checked for lines that are too long, too many lines, reading too fast (characters per second), too short or too long on screen, overlapping the next cue, and no gap before the next cue. Read more about reading speed and line length.

What does it fix automatically?

It rebalances line breaks, preferring punctuation. It splits cues that need too many lines and shares their time by text length. It closes overlaps, keeps a minimum gap, and gives fast or short cues more time from the free space around them. It can also remove [MUSIC] style tags, speaker names and italics. Two-speaker dash lines are kept intact.

What do the Streaming, Broadcast and Social vertical presets mean?

Streaming allows 42 characters per line, 2 lines and 20 characters per second, with cues between 0.83 and 7 seconds. Broadcast allows 37 characters and 15 characters per second, with cues between 1 and 6 seconds. Social vertical allows 28 characters and 17 characters per second, for 9:16 video.

Streaming matches the limits Netflix publishes for English subtitles on adult programmes, and Broadcast uses the 37 character line of BBC broadcast subtitles. Subtidy is not affiliated with Netflix or the BBC.

Which formats can I open and export?

Subtidy opens SRT, WebVTT and ASS/SSA files in UTF-8, UTF-16 or Windows-1252. Free exports SRT. Pro also exports WebVTT, ASS (1920 by 1080, ready for burning in with FFmpeg) and a plain text transcript.

Will the files work in Premiere Pro, DaVinci Resolve and YouTube?

Yes. SRT exports open in Premiere Pro, DaVinci Resolve, Final Cut Pro and YouTube. When the text has characters beyond basic English, Subtidy saves the SRT as UTF-8 with a byte order mark, which helps Premiere Pro detect the encoding.

Does it handle Urdu, Arabic and other right-to-left text?

Yes. Right-to-left text displays correctly in the preview and the cue list, and line balancing recognises Urdu and Arabic punctuation when it chooses where to break.

What is the difference between Free and Pro?

Free includes every automatic fix, the three presets, the 16:9 title safe preview, the full QC report and SRT export, one file at a time. Pro adds batch processing with a zip download, custom limits, the 9:16 safe-zone check, WebVTT, ASS and transcript export, frame rate conversion and timing shift, for $5 a month or $39 a year.

Can I get a refund?

Yes. Every payment has a 14-day money-back guarantee, and you can cancel any time from Your plan. See the refund policy.

Guides

The rules behind each check, with the published limits and how to fix each problem.