File type / image
.sub
Raster or vector imagery used in design systems and web experiences.
Best for: Brand assets, UI elements, product screenshots, and creative deliverables.
Type family
image
Subtype
vnd.dvb.subtitle
Default handling
Inline-capable
Handling verdict
Modern browsers can usually display this media type without downloading it first.
Use a format-aware application rather than a plain-text editor.
The registry does not declare compressibility; compare encoded size before enabling it globally.
Images are usually safe. Be mindful of metadata if you're sharing externally.
HTTP response headers
Content-Type: image/vnd.dvb.subtitle
Content-Disposition: inline; filename="example.sub"
X-Content-Type-Options: nosniffThe MIME type describes the payload, Content-Disposition controls whether the browser previews or saves it, and nosniff prevents the browser from silently substituting a guessed type.
HTML file input
accept=".sub,image/vnd.dvb.subtitle"Use this value on <input type="file"> to steer the picker toward .sub, its known aliases, and files reporting image/vnd.dvb.subtitle. It improves selection, but it is not validation—check the bytes again after upload.
Registry ledger
declared valuesMIME type
image/vnd.dvb.subtitle
Registry source
iana
Character set
Not declared
Compressible
Not declared
Known aliases
None listed
Same MIME type
No sibling record
How to work with .sub
operational notesOpen it with the format-aware tool first
Start with Preview, Figma, Adobe Photoshop. Optimize dimensions and compression so render blocks don't slow down page loads. If the file came from someone else, keep the original untouched and work on a copy so a failed conversion cannot destroy the only source.
Safety note
Images are usually safe. Be mindful of metadata if you're sharing externally.