MIME Type Lookup

The MIME Type Lookup tells you the correct content type to use for a file based on its extension, drawing on a built-in table of well over a hundred common media types. You paste file names or bare extensions, one per line, and the tool returns the matching MIME type for each, such as the type for a PDF, a PNG image, or a JSON document. This is exactly the value you need when setting a Content-Type header, configuring a server, or validating uploads.

The tool also works in reverse. Switch on reverse lookup mode and paste MIME types instead, and it lists every file extension known to map to each type. That is handy when you are reading a header or an API response and want to know which file extensions are appropriate, or when building an allow-list of acceptable upload formats from a set of content types you already trust.

Because the entire mapping is bundled into the page, lookups are instant and completely offline. Nothing you paste is uploaded, so you can safely check extensions and types from internal projects and private file lists. Unknown extensions fall back to the generic binary type, mirroring how a cautious server would treat a file it does not recognise.

Features

• Maps file extensions to MIME content types using a built-in table of over a hundred common formats.
• Accepts full file names or bare extensions and strips everything before the final dot automatically.
• Offers a reverse mode that lists all known extensions for each MIME type you paste.
• Falls back to the generic application octet-stream type for extensions it does not recognise.
• Covers images, audio, video, documents, archives, fonts, code and web formats in one place.
• Processes a whole pasted list at once and returns a clean, exportable table of results.
• Runs fully in your browser with no upload, so private file lists never leave your device.

How to use MIME Type Lookup

1. Paste file names or extensions into the input box, one per line, such as report.pdf or png.
2. Leave reverse mode off to look up the MIME type for each extension you entered.
3. Turn reverse mode on and paste MIME types instead to find the extensions that map to them.
4. Read the table to see each input alongside its detected extension and content type.
5. Copy or download the results to use in server config, upload validation or documentation.

Benefits

• Backend developers set accurate Content-Type headers so browsers render files correctly.
• DevOps engineers configure web servers and CDNs with the right media types for each extension.
• Security teams build upload allow-lists by mapping trusted content types to permitted extensions.
• API builders confirm which extensions correspond to a content type returned by a service.
• Support staff diagnose downloads that open incorrectly because of a wrong or missing MIME type.
• Because the table is local, private file names and project details never leave your browser.

A MIME type, also called a media type or content type, is a short label such as the one used for PDF or PNG that tells software how to interpret a file. Web servers send it in the Content-Type header, and browsers use it to decide whether to display a file inline, download it, or run it. Sending the wrong type is a common cause of files that download as gibberish or fail to render.

This tool reads only the text after the final dot in whatever you paste, so both a full path and a bare extension work the same way. Extensions are matched case-insensitively. When an extension is not in the table, the result is the generic binary type, which is the safe default a server uses to force a download rather than guess. In reverse mode, note that several extensions can legitimately share one content type.

The whole mapping ships with the page, so lookups are instant, work offline, and never send your input anywhere, making the tool suitable for confidential project files. Keep in mind that a file extension is only a hint about content, not a guarantee, so for security-sensitive uploads you should also inspect the actual bytes of a file rather than trusting its name alone.