How to use the MIME Type Lookup
- Type an extension (
webp,.mjs) or part of a MIME type (font/,json), or filter by category. - Click a row to see the
Content-Typeheader and the Nginx and Apache configuration lines. - Not sure what a file really is? Drop it on the box — the tool checks its magic bytes and compares them with the extension.
Why the MIME type matters
Browsers trust the Content-Type header, not the file extension. A wrong type causes real bugs:
- JavaScript modules served as
text/plainare blocked: “Failed to load module script… strict MIME type checking”. - Fonts served as
application/octet-streammay be rejected or not cached; usefont/woff2. - SVG without
image/svg+xmlshows as text or a download instead of an image. - WebAssembly needs
application/wasmforinstantiateStreaming(). - With
X-Content-Type-Options: nosniff(recommended — check it with the Security Headers Checker) browsers stop guessing entirely.
Most-used web types
| Extension | MIME type |
|---|---|
| .html | text/html; charset=utf-8 |
| .css | text/css |
| .js, .mjs | text/javascript |
| .json | application/json |
| .svg | image/svg+xml |
| .webp / .avif | image/webp / image/avif |
| .woff2 | font/woff2 |
| .webmanifest | application/manifest+json |
Check what your server actually sends with the HTTP Header Checker, and configure it with the Nginx Config Generator. To embed small files directly, use Image to Base64.
Tools that pair well with the MIME Type Lookup
- HTTP Status Codes — Every standard HTTP response code explained in plain English, with when to use it and how it affects SEO.
- Unicode Character Inspector — Paste anything to see what it’s really made of: each character’s name, code point, UTF-8 bytes and HTML code.
- Ping Test — Measure how fast a server responds: enter a host and get the round-trip latency, jitter and failed attempts over several pings — measured from our server with a TCP ping to the port you choose.
- Port Checker — Test whether a server accepts connections on specific ports — web (80/443), mail (25/587/993), SSH, databases or remote desktop — and see which are open, closed or filtered by a firewall.
Frequently asked questions
What is the MIME type for JavaScript?
text/javascript is the official type (RFC 9239). application/javascript still works in all browsers, but new configurations should use text/javascript for .js and .mjs.
What does application/octet-stream mean?
It means “arbitrary binary data”. Servers use it when they don’t know the type; browsers usually download such files instead of displaying them.
How is the file type detected?
The tool reads the first bytes of the file in your browser and compares them with known signatures (PNG, JPEG, GIF, WebP, PDF, ZIP, GZIP, WebAssembly, MP4, SVG and more). The file is never uploaded.
What is the MIME type for .woff2 fonts?
font/woff2. Older servers often use application/font-woff2 or application/octet-stream; both work but font/woff2 is the standard.