🗂️MIME Type Lookup

About this tool

Type an extension such as .webp or part of a MIME type such as image/ to search a list of over 200 common types, and copy any result. To check a file, choose it below: the tool reads its first few kilobytes on your device, identifies the format from its signature, and compares that with what the extension suggests and what the browser reports.

How MIME types and file signatures work

A MIME type, officially a media type, is a label such as text/html, image/png or application/pdf that tells software how to handle a file. Web servers send it in the Content-Type header, and browsers use it to decide whether to display, play or download a response. Servers usually pick the type from the file extension, so a misconfigured server, or a file with the wrong extension, can cause downloads instead of previews, blocked scripts or fonts that won't load. Modern browsers are strict about some types: JavaScript must be served as text/javascript and stylesheets as text/css, especially with the X-Content-Type-Options: nosniff header. Extensions can be changed freely, but most binary formats begin with a fixed signature, or magic bytes. A PNG always starts with the bytes 89 50 4E 47, a PDF with %PDF, a ZIP with PK, and MP4, HEIC and AVIF files contain the marker ftyp followed by a brand code. Checking those bytes reveals what a file really is. Honest limits: Office documents, EPUB books and Android APKs are ZIP files inside, and plain-text formats such as CSV, JSON and source code have no signature, so they can only be recognised as text. The list covers common types rather than the full IANA registry. The hash generator fingerprints files and the Base64 encoder converts them to text. How checksums verify downloads and backups — and which one to use explains file integrity checks.

Frequently asked questions