Look up MIME types by file extension and find file extensions for MIME types with a searchable database.
MIME Type Lookup answers two related questions: which MIME type is associated with a file extension, and which extensions are associated with a MIME type. Enter one side of the association to search the browser-based database for the other. The lookup is useful when checking filenames, HTTP metadata, upload rules, or server configuration. The important limitation is that an extension-to-type match describes a conventional association. It does not inspect the file, prove its contents, or guarantee how a browser will handle it.
Search with a file extension when you need its commonly associated media type. The result is a database mapping based on the suffix, not an analysis of the file's bytes. This distinction matters for renamed, malformed, or deliberately misleading files. The lookup also cannot tell whether an HTTP server is actually sending the returned value in its Content-Type header.
Search with a media type in type/subtype form when you need associated filename extensions. A reverse lookup can return more than one extension because several suffixes may conventionally represent the same format. The relationship is not necessarily one-to-one, and a listed extension is a naming convention rather than a requirement imposed on every file carrying that media type.
No. The mapping identifies a conventional media type for the extension, but browser behavior depends on more than that association. The actual Content-Type response header, Content-Disposition, browser capabilities, security policies, and the validity of the file all matter. A correct lookup result can still accompany a download prompt or an unsupported-format response.
No. Extension lookup uses the name supplied to find a stored association; it does not inspect file signatures or parse content. If the extension is absent or misleading, use a content-aware file identification or validation method. If the media type is already known independently, reverse lookup can suggest conventional extensions without verifying the file.
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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