Free Tool
SRT Validator
Drop an .srt file and get a list of errors and warnings with the block number for each one. Runs in your browser — the file is never uploaded.
- Runs in your browser
- Nothing uploaded
- No signup
Drop your file here
or
Supports .srt, .vtt, .txt files
Add SRT files (2+)
Result
How it works
SRT Validator in three steps
Drop Your SRT File
Drag and drop or browse to select an SRT subtitle file from your computer.
Instant Validation
The validator checks sequence numbers, timestamp format, timing overlaps, and empty cues.
Review Results
See a clear report of errors and warnings with line numbers for easy fixing.
Why a player refuses to load your subtitles
SubRip is unforgiving about small things. A period instead of a comma in the milliseconds, a missing sequence number, a stray blank line — and the player either skips part of the file or shows nothing at all. It almost never tells you why: the subtitles simply do not appear.
This validator walks the file block by block and tells you what is wrong and exactly where. The check runs in your browser; the file is never uploaded.
What gets checked
Flagged as errors: a block with fewer than two lines, a missing or unreadable sequence number, a missing or unparseable timecode line, and an end time that is not after the start time. Flagged as warnings: a sequence number out of order, a timecode that is not in hh:mm:ss,mmm form, an overlap with the previous cue, empty subtitle text, and a cue that stays on screen longer than 15 seconds.
The split matters. An error usually means the file will not load or will silently lose blocks. A warning means the file works but a viewer will notice something is off — a subtitle hanging too long, or two cues stacking on top of each other.
What to do with the report
Small fixes are easiest by hand: the report gives you block numbers, and an .srt opens in any text editor. If overlaps run through the whole file, rebuilding it is usually faster than patching cue by cue.
If the structure checks out but the subtitles still drift against the speech, the format is not the problem — use the time shift tool, which moves every timecode at once. And if the file was assembled from several parts, look at the joins first: that is where overlaps normally appear.
Answers
SRT validation — frequently asked questions
What is the difference between an error and a warning?
An error means the block breaks the format and the player will most likely drop it or refuse the file. A warning means the file still works but something is off-spec: numbering out of order, cues overlapping, or one cue sitting on screen far too long.
Why is a timecode with a period a problem?
Because SubRip separates milliseconds with a comma; the period is the WebVTT convention. Many players will still open such a file, but some tools reject it outright, so the validator points it out.
What counts as an overlap?
A cue that starts before the previous one has ended. On screen it looks like two lines at once or like flickering text. The report shows both the start time of the current cue and the end time of the previous one.
Why is a duration over 15 seconds flagged?
It is not a format violation, it is a quality note: a cue on screen for more than fifteen seconds usually means two blocks were merged or the end timecode is wrong. The file itself remains perfectly valid.
Is my file uploaded to a server?
No. Parsing happens in your browser and the file is never transmitted or stored, so you can check confidential material safely.
Does the validator fix the errors?
No, it only reports them with block numbers. Corrections are made by hand in a text editor — SubRip files are simple enough for that.
Can I validate a .vtt file?
The validator targets SubRip. Convert a WebVTT file with the VTT to SRT converter first, then check the result here.
The file passes but the subtitles still do not match the speech
Then the format is fine and the timing is not: the file was made for a different cut of the video. That is what the subtitle time shift tool is for — it moves every timecode at once.
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