b2KIT

Content-Type Reference

Browse and search MIME content types with associated file extensions, descriptions, and usage examples.

Tested tool guide Tested browser tools Checked August 15, 2026

What Content-Type Reference does and how it behaves

This tool is a searchable table pairing registered MIME content types with the file extensions they're normally served under, a plain-language description, and a short usage note. Typing an extension, a type/subtype string, or a keyword filters the list to matching rows as you go. The catalog is a curated snapshot built from IANA registrations and common practice, not a live query against the registry, so a type added recently, or an obscure vendor-specific subtype like application/vnd.*, may be missing or shown with an older description.

How the result is produced

1

Instant substring search

As you type, the tool filters its table by matching your text against the type/subtype string, the file extension, and the description field simultaneously. A search for 'audio' surfaces every row where any of those three fields contains that substring, so results include subtypes like audio/mpeg alongside unrelated rows whose description happens to mention audio. The same applies to a search for 'json': IANA has registered many types whose subtype ends in the structured-syntax suffix '+json' (RFC 6839), such as application/ld+json and application/geo+json, so a keyword search for 'json' can return several rows, not a single exact match.

2

Curated table, not a live registry

Each row pairs a registered type/subtype with the extension(s) commonly used for it, a short plain-language description, and typically a note on where you'd send it, such as a Content-Type header or an Accept value. The data is a bundled, periodically updated dataset built from IANA's registry and common practice, not a live network call to iana.org.

Good uses

  • Setting the correct Content-Type header when serving or uploading a file with a known extension, e.g. what to send for a .woff2 font
  • Decoding an unfamiliar MIME type spotted in an HTTP response, email attachment, or API payload, such as application/x-www-form-urlencoded
  • Deciding which extensions or type strings to whitelist in a file-upload form's accept attribute or server-side validation

Limits and checks

  • The table is a static, curated snapshot - it can lag behind newly registered types and vendor-specific application/vnd.* subtypes, so an absent entry doesn't mean the type is invalid
  • Extension-to-type mapping is many-to-many in practice: the same extension can be served under more than one MIME type depending on the source (some tools label .csv as application/vnd.ms-excel instead of text/csv), so a listed pairing is a common convention, not a guarantee of what any given server actually sends
  • This is a text lookup over reference data, not a file inspector - it cannot examine an actual file's bytes or magic number, so it won't tell you the true type of a mislabeled or extensionless file on your disk

Common questions

Can I drop a file in to see its real MIME type?

No. This tool only searches a static reference table by extension, type name, or keyword - it never reads file contents, so it can't identify a file whose extension is missing or wrong.

Is this the same list IANA publishes?

It's a curated subset drawn from IANA's registrations and common usage, kept for quick lookup, not a live mirror. For the current authoritative record of any type, check the IANA Media Types registry directly.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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