MIME Type Lookup
Look up a file extension (.pdf, .docx, .png...) or a MIME type (image/png, application/pdf...) and find its equivalent.
What a MIME type is
It's a standard string (e.g. application/pdf, image/png) that identifies a file's or an HTTP response's actual format — a browser, server, or API uses it to know how to interpret that content, regardless of the file's extension (which can be manipulated or missing).
Where it's used
In an HTTP request's or response's Content-Type header, in a <input type="file">'s accept attribute, and generally in any API that needs to know what kind of data it's handling without relying only on the filename.