MIME Type Finder
Match common file names and extensions with media types, or inspect a Content-Type value while keeping filename conventions separate from actual file-content detection.
Try app.js, archive.tar.gz, .json, application/json, or text/html; charset=utf-8.
Media Type Result
Common mappings are bundled for quick lookup; the IANA registry contains many more registered media types.
Extension or media-type details will appear here.
A Filename Can Suggest a Format; It Cannot Prove One
A media type describes transferred content. A filename extension is only a naming convention. Renaming HTML, executable data, or a ZIP archive to photo.jpg does not turn those bytes into a JPEG image.
That distinction is important in upload handling. Extension checks are useful for user feedback, but security-sensitive validation needs server-side inspection appropriate to the format and safe storage and serving rules for user-controlled content.
Content-Type Has a Type, a Subtype, and Sometimes Parameters
In Content-Type: text/html; charset=utf-8, text/html is the media type and charset=utf-8 is a parameter. Parameters are defined by the media type's specification; they are not a universal list that can be copied from one type to another.
Pasting the full Content-Type: field is accepted, but lookup is performed on the base type/subtype. A wildcard such as image/* is different: it is a media range used in negotiation fields such as Accept, not a concrete Content-Type for one representation.
archive.tar.gz Describes Two Layers
The last extension in archive.tar.gz describes the outer gzip layer, so .gz maps to application/gzip. The filename still does not prove that the decompressed bytes form a TAR archive. Compound names are best read as processing hints rather than byte-level evidence.
Registration and Common Web Usage Are Not the Same List
IANA maintains the authoritative registry of media-type names, but it is not a universal filename-extension database. Some extension mappings come from platform or browser conventions, and some widely seen web values are not main-registry registrations.
For example, text/javascript is the registered JavaScript type and IANA marks application/javascriptobsolete in its favor. application/yaml is registered for YAML. Values such as audio/wav and video/webm are common in web software but are kept clearly separate from claims about IANA registration.
+json and +xml Tell You About Syntax, Not Registration
A structured syntax suffix can let generic software recognize an underlying representation family. A subtype ending in +json signals JSON-based representation semantics;+xml does the same for XML. That suffix does not by itself prove that the complete media-type name is registered or appropriate for a particular protocol.
SVG and MIME Sniffing Need Separate Security Decisions
image/svg+xml is an image media type, but SVG is XML-based and can contain active features. Upload rules that treat every image/* value as an inert bitmap can therefore create a security boundary that is much weaker than it looks.
Browsers can also apply MIME-sniffing behavior in some contexts when a response type is absent or ambiguous. A filename lookup does not reproduce those algorithms. For a live HTTP problem, inspect the real Content-Type, X-Content-Type-Options, request context, and browser behavior.
When the Exact Registration Matters
The IANA Media Types registry is the place to confirm whether a type/subtype is registered, obsoleted, or associated with a particular specification. The registration framework is described by RFC 6838, while individual types often point to their own defining RFC or standards document.