Validate TTML before you ship
Strict TTML validator catches malformed timestamps, encoding glitches, and spec violations before your file lands at a fussy player or distribution platform.
Input
TTML file
Drop, paste, or pick
Output
Pass / fail report
Errors with line numbers
- Runs 100% in your browser — nothing uploads
See it in action
TTML validator report
What you put in → what you get back
TTML input (with intentional errors)
What you provide
<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/ns/ttml">
<body>
<div>
<p begin="00:00:12.340" end="00:00:15.780">Hello, it's me</p>
<p begin="00:00:15.780" end="00:00:19.200">I was wondering if after all</p>
<p begin="00:00:19.200" end="00:00:22.840">these years you'd like to meet</p>
</div>
</body>
</tt>Validation report
What you receive
✓ Valid TTML Format : TTML Cues : 3 Encoding : UTF-8 Timestamps: monotonic ✓ Required fields: present ✓ Ready to ship.
Step-by-step guide
How to use this tool
- 01
Drop or paste TTML
Either input works — drag in a file, paste from clipboard, or type directly.
- 02
Strict parser runs
We check every timestamp, encoding, and required field against the spec.
- 03
Read the error report
If valid, you get a green check. If not, we list each error with line numbers — no guesswork.
Key features
Why use this tool
Spec-strict parser
We follow the TTML reference grammar — any deviation is flagged.
Helpful error messages
Each error names the line number and what's wrong, not just 'parse failure on line 42'.
Privacy-first
Validation runs in your browser. Use it on unreleased subtitles without leaking them anywhere.
Format mismatch detection
Pasted SRT into the TTML validator? We'll suggest switching to the right one before you waste time debugging.
Common use cases
Who this tool is for
Pre-delivery QA
Catch broken subtitles before sending to a client or platform that will reject the whole batch.
Player crash debugging
When a player rejects a file with a generic error, validate here to find the actual offending line.
Mass-cleanup
Identify which files in a folder need fixing — drop each one in for a fast pass/fail.
Questions answered
Frequently asked questions
Found errors? Fix them in seconds
Convert, repair, or re-time using one of our other tools.