File Tools
Free Online File Extension Lookup
Type a file extension (like .docx or .png) to find out what it is, its typical MIME type, and which apps commonly open it.
How to use the file Extension Lookup
- Type a file extension into the box — with or without the leading dot.
- Click 'Look up'.
- See what the file type is, its common MIME type, and which applications typically open it.
Example
Looking up .docx returns "Microsoft Word Document", its MIME type, and notes that it's commonly opened with Microsoft Word, Google Docs, or LibreOffice Writer.
Why look up a file extension?
Unfamiliar file extensions show up all the time — email attachments, downloads, or files sent by colleagues. This tool gives you a quick answer on what a file actually is before you decide whether, and how, to open it.
Covers common everyday formats
The lookup table covers frequently seen document, image, audio, video, code and archive extensions, with more being added as the tool grows.
Frequently asked questions
The lookup table currently covers common formats and is expanded regularly; use the contact link if you'd like a specific extension added.
No, this tool only explains what a file type generally is — it doesn't scan or analyze any actual file you have.
No, you only need to type the extension itself, like 'pdf' or '.pdf' — no file upload required.
No, it lists commonly used applications for that file type in general, not what's installed on your particular device.