Convert between file extensions and MIME types. Part of the DevTools Surf developer suite. Browse more tools in the Networking collection.
Use Cases
Setting correct Content-Type headers for API file responses
Configuring web server MIME type mappings for static assets
Validating file upload types in backend middleware
Looking up media types for Content-Type negotiation in APIs
Tips
Search by file extension to find the correct Content-Type
Look up MIME types for proper API response headers
Verify multipart form data types for file upload endpoints
Fun Facts
MIME (Multipurpose Internet Mail Extensions) was defined in RFC 1341 in 1992, originally for extending email beyond plain ASCII text.
The application/octet-stream MIME type is the default for unknown binary files, effectively meaning 'download this, don't display it.'
There are over 1,500 registered MIME types with IANA, but application/json wasn't officially registered until RFC 4627 in 2006.
FAQ
What MIMEs are in the database?
~800 standard types from IANA's registry. Extension-to-MIME and MIME-to-extension lookups both work.
What's the MIME for .mjs?
text/javascript. The spec settled on this (ES modules use the same MIME as regular JS). .mjs helps servers and browsers disambiguate ES modules from CommonJS.
Why do I care about Content-Type?
Servers send it; browsers use it to decide how to render. Wrong Content-Type on JSON causes browsers to show raw JSON as text or refuse to parse it.
What's application/octet-stream?
The 'unknown binary' type. Fallback when the server doesn't know. Browsers typically download it rather than render inline.
