✳ VALIDATOR · MASTODON
Subtitle validator for Mastodon
Pick a subtitle file. Koldflux reads metadata locally and reports PASS / WARNING / FAIL / UNKNOWN against Mastodon. Nothing uploaded.
Extension and MIME type are labels, not proof of the container. Dimensions and duration come from this browser's media reader. Files and measurements are not sent anywhere.
What this checks
- Container compatibility (does Mastodon accept this extension)
- File size vs. Mastodon max
- Aspect ratio vs. Mastodon recommended
- Caption character and duration limits
Convert a failing file in one click: /tools/convert
Automate this in Koldflux