File Extensions
Find out what a file format is, its MIME type and which program opens it. 64 extensions, searchable by name or extension.
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Documents (9)
Spreadsheets (4)
Images (11)
Audio (6)
Video (6)
Archives (6)
Code & web (7)
Executables (5)
Frequently asked questions
What is a file extension?
A file extension is the short suffix after the dot in a file name (e.g. ".pdf" in doc.pdf). It tells the operating system what format the file is and which program should open it.
How do I open a file with an unknown extension?
First identify the format here to see which program supports it, then install that program. If the extension is missing or wrong, rename the file with the correct extension or ask the sender what format it is.
Is it safe to open any file?
No. Executable formats (.exe, .msi, .apk, .bat, .jar) can contain malicious code — open them only from sources you trust. Documents and media are safer, but can still carry risk through macros or vulnerabilities.
Does changing the extension change the format?
No. Renaming a file (e.g. from .txt to .jpg) does not convert its contents — it only misleads the system about which program to use. To truly change a format you need a converter.
What is a MIME type?
A MIME type (e.g. "application/pdf") is a standard identifier that web servers and browsers use to describe a file’s kind independently of its extension.