SRT & VTT validator
Paste or load a subtitle file and pick the app it is headed to. The report names the exact line Premiere Pro, DaVinci Resolve, Final Cut, Avid, YouTube or a strict player will choke on, plus overlaps and reading speed. One click repairs the structure without touching your timing.
Check against
The report appears here: the exact line each app will choke on, overlaps, reading speed (chars/sec), and line-length checks against the common 17 cps / 42-character limits. Then one click repairs the structural problems without touching your timing.
What each app trips over
Premiere Pro, Resolve, Final Cut and Avidread subtitles into a caption track. They expect the SRT shape exactly: a counter, a timing line with commas, text, a blank line. Dots instead of commas, a missing blank line, or a cue out of order is where most “file not supported” messages come from. Inline <i> tags and {\an8} blocks may appear as literal text, and overlapping cues fight for the single track.
YouTube and browsers are forgiving about counters and separators but strict about the WebVTT header, undecodable characters and backwards timing. They render italics and show overlapping cues side by side, so those are not flagged when you choose YouTube.
Errors are things that stop a parser. Warnings are things that break viewers: overlaps, sub-second flashes, three-line walls of text, cues over seven seconds, and reading speeds past about 17 characters per second. Thresholds follow the conventions most streaming and broadcast style guides share: two lines of about 42 characters, 17 cps for adult programming. Treat warnings as review flags, not failures.
FAQ
Why won't Premiere Pro import my SRT?
Nine times out of ten the file is not really SRT: WebVTT-style dot timestamps (00:00:01.000), a WEBVTT header hiding in a file renamed .srt, a missing blank line between two cues, or a cue whose end time comes before its start. Pick "Premiere Pro" above and the report names the line. "Fix safely" repairs the structural ones; timing problems stay yours to decide.
Why is my SRT not working in DaVinci Resolve?
Resolve imports subtitles as a track and is strict about the file shape: comma separators, counters, one blank line between cues, cues in order. A file exported from a web tool with dots and no counters is the usual culprit. The Resolve check flags every line that breaks that shape and the fixer rewrites it without moving a cue.
YouTube says my subtitle file has a problem. What is wrong with it?
YouTube is tolerant about separators and counters but rejects a .vtt without its WEBVTT header, cues with commas in a VTT, end-before-start timing, and undecodable bytes from a file saved in a legacy encoding. Choose "YouTube" to see only what matters there; inline <i> and <b> tags are fine on YouTube and are not flagged.
What does "Fix safely" change, and what does it leave alone?
It only touches structure: timestamp separators (commas for SRT, dots for WebVTT), counters, missing blank lines, cue order, line endings, the byte-order mark, ASS override blocks, and, for editing apps only, inline HTML tags they would show as literal text. It never edits a timestamp value, never merges or drops a cue, and never resolves an overlap or shortens a long cue. Those need an editorial decision, so they stay in the report.
Can overlapping subtitles break an import?
YouTube and browsers show both cues. Premiere, Resolve, Final Cut and Avid put captions on one track and may trim or drop the overlapping cue. The report gives the overlap in milliseconds so you can decide which cue gives way; the fixer will not choose for you.
What is CPS (characters per second) in subtitling?
Reading speed: the cue's character count divided by its on-screen duration. Common guidelines cap adult programming at about 17 cps. Faster than that and viewers cannot finish reading before the cue leaves. AI transcript exports are the usual source of over-speed cues.
Does it check WebVTT too?
Yes. A file with a WEBVTT header, or named .vtt, is checked with WebVTT rules: dots are correct, cue settings after the timing are allowed, NOTE blocks are skipped, and commas are flagged instead.
Is my file uploaded anywhere?
No. Checking and fixing both run entirely in your browser. Nothing is sent to a server.
Related tools & converters
- SRT cleanerStrip SDH annotations, speaker labels, and tags the report flagged.
- SRT shifterFix a constant sync offset the validator surfaced.
- VTT to SRTTurn a web subtitle file into the SRT editing apps expect.
- SRT to VTTConvert a validated file for web players and YouTube.
- SRT to Premiere JSONBring the text into Premiere's Text panel with timing.
- SRT to CSVEdit problem cues in a spreadsheet, then convert back.
- Whisper JSON to SRTWhere fast, unreadable AI cues usually come from.