Files & identity · Concept
What Is a MIME Type?
When you upload or download over HTTP, systems often trust Content-Type more than the filename. MIME types map formats to labels: image/png, application/pdf, audio/mpeg.
Quick take: A MIME type (media type) is a standard label like image/jpeg or video/mp4 that tells browsers and servers how to treat a file’s contents.
Anatomy
type/subtype — image/webp, application/json, text/csv. Parameters sometimes follow (charset=utf-8).
MIME vs extension
A server may send image/jpeg for a URL ending in .jpg. If MIME and bytes disagree, browsers can behave oddly. Conversion tools should emit matching extensions and types.
Why uploads reject files
CMS and APIs whitelist MIME types. HEIC may be image/heic — many servers only allow image/jpeg and image/png.
Key points
- MIME types label content for the web.
- They pair with formats, not with apps.
- Upload filters often key off MIME + extension.
Examples
image/jpeg
JPG photos.
video/mp4
MP4 media files.
application/pdf
PDF documents.
Try it in a converter
Concepts stick better with a real file — processing stays in your browser.
Related concepts
FAQ
Do MIME types change when I convert?
Yes — the new file should advertise the target type (e.g. image/webp after PNG → WebP).
Browse all conversion concepts or jump to converters.