MIME Type Lookup - Free Online Tool
MIME Type Lookup
Convert Between File Extensions and MIME Types
Understanding MIME Types
Content-Type Headers
Web servers use MIME types in the Content-Type header to tell browsers how to interpret a file's data.
File Upload Validation
Look up the expected MIME type for a file extension when writing upload validation logic.
Email Attachments
MIME originated in email (Multipurpose Internet Mail Extensions) to describe attachment content types.
Client-Side Only
All lookups happen locally in your browser against a bundled reference table — no data is ever sent to a server.
Extensions Aren't Always Reliable
A file's extension is just a naming convention — it doesn't guarantee the file's actual content matches. Servers and applications that need to trust content type should ideally verify the file's actual binary signature (magic bytes) rather than relying on the extension or a client-supplied MIME type alone, especially for security-sensitive upload handling.
Key Takeaways
- Bidirectional Lookup: Search by extension or by MIME type — the tool detects which you entered.
- Multiple Extensions Handled: Some MIME types map to more than one common extension (e.g. .jpg and .jpeg).
- Client-Side Only: All lookups happen locally in your browser — no data is ever sent to a server.