MIME Types

Why MIME Types Matter

Every file on the web has a MIME type — a label like `image/png` or `application/pdf` that tells the browser what to do with it. Correct MIME types mean images render inline, PDFs open in the reader, videos stream without download prompts, and downloads get the right filename extension. Wrong MIME types are one of the quietest common bugs in web development.

Where They Come From

MIME types are maintained by IANA (Internet Assigned Numbers Authority) in a public registry. The `mime-db` package that powers this tool mirrors that registry and is updated regularly by the open-source community. When a new file format emerges — think WebP, AVIF, WebAssembly — its MIME type gets registered with IANA and propagates out to every server and browser that uses the mime-db dataset.

Common Gotchas

Not every extension maps to one MIME type: `.m4a` can be `audio/mp4` or `audio/x-m4a`. Not every MIME type has a registered extension. Some extensions are ambiguous across platforms (`.bin` is used for everything). And custom content types are common inside organizations (e.g., `application/vnd.company.thing+json`) — IANA's registry only covers the public ones.

Use Cases for This Tool

Look up a type when configuring a `Content-Type` header. Verify an extension when building a file picker's `accept` attribute. Debug 'wrong file type' errors by checking what MIME your server is actually sending. Filter by category to browse everything in a domain (all audio, all video, all fonts). Click any row to copy the MIME string for paste.

What's a MIME type?

A label that tells browsers and servers what kind of file they're dealing with — e.g., `image/png` or `application/pdf`. It drives whether your browser renders, downloads, or rejects a file.

Which extensions map to multiple MIME types?

Many. For example `.m4a` can be `audio/mp4` or `audio/x-m4a` depending on the system. The tool shows all registered variants from the mime-db dataset.

How current is this list?

The data comes from `mime-db`, which mirrors the IANA registry and is updated by the open-source community. We bundle the latest snapshot with each deploy.