MIME Lookup — Identify File Types by Extension or Magic Bytes
Look up MIME types by file extension or magic bytes. 1,800+ entries from IANA registry — in your browser, no upload.
MIME Type Lookup
Look up MIME types by file extension, or find the correct extension for a MIME type. Supports 100+ common formats covering images, documents, audio, video, code, and archives. Works entirely in your browser.
MIME types are the universal language of file identification on the internet. Every HTTP response, every email attachment, every file upload form uses a Content-Type header that declares the file’s format in the type/subtype convention. The IANA media types registry is the single source of truth, and every web server, every CDN, and every browser consults it. A MIME lookup tool saves the trip to the IANA website for the common case: you have a file extension or a few bytes of content and you need the Content-Type string to paste into a server config, a response header, or a validation rule.
How to use
Enter a file extension or MIME type
Type `.pdf` to get `application/pdf`, or type `image/png` to get `.png`. The lookup covers all IANA-registered types and common vendor extensions.
Paste magic bytes
Paste the first few bytes of a file as hex (e.g. `%PDF`, `PNG`, `GIF89a`) and the tool identifies the MIME type from the file signature.
Copy the result
Click to copy the MIME type or extension. Useful for Content-Type headers, server configuration, and debugging file upload validation errors.
Frequently asked
What's the difference between IANA and vendor MIME types?
IANA maintains the official registry. Vendor types (`application/vnd.*`) are registered by companies for proprietary formats. The lookup covers both and flags IANA-registered entries with a checkmark.
Can it identify a file without an extension?
Yes — paste the first few bytes as hex or as a recognisable text prefix and the tool matches against known file signatures. This is equivalent to the `file` command on Unix.
Does it cover the most recent IANA registrations?
The lookup table is based on the IANA media types registry as of 2024. New registrations after that date may not appear. Submit an update for any missing type.
What about application/octet-stream?
`.bin`, `.exe`, `.dll`, and generic binary files all map to `application/octet-stream`. A file with no known extension and no matching magic bytes will also return this default type — it's the most common cause of 'file type not recognised' errors.
Limitations
- Static lookup tableThe tool reads from a static table. It does not inspect the file's actual content beyond the first bytes you paste. Magic-byte detection is heuristic, not exhaustive.
- No charset detectionFor text files, the tool returns the MIME type but not the charset. Add `; charset=utf-8` to the Content-Type header by hand based on the document's actual encoding.
Platform notes
- macOS
- The `file --mime-type filename` command in Terminal does the same thing with system-level magic databases. The browser tool is the right pick for one-off lookups without a terminal.
- Web
- Runs entirely client-side. No upload. The lookup is instant.