Uuencoded (compressed) file archive (ASCII)
File type: Encoded and encrypted file
A .uu file is an ASCII-encoded archive created with the uuencode format. It represents binary archive data as text so it could be transferred through systems such as email and USENET.
The data was often compressed before it was uuencoded. The corresponding decoding process is called uudecode.
File type category:
Encoded and encrypted file
Date updated: October 25, 2026
Record marked as obsolete and not updated for a long time.
The uu file extension identifies a Uuencoded (compressed) file archive (ASCII). Uuencoded files were widely used with email and USENET to carry binary files through text-only communication systems.
A uuencoded file contains ASCII text representing the encoded archive data. The original archive must be decoded before its contents can be used. Commonly associated MIME types include application/uue, text/x-uuencode, and application/octet-stream.
The format is obsolete and is rarely used for new files. Windows programs associated with this record include WinZip, ALZip, and ZipZag; WinZip Mac Edition is available for Apple macOS and Mac OS X.
On Microsoft Windows, open a .uu file with WinZip, ALZip, or ZipZag. On Apple macOS or Mac OS X, use WinZip Mac Edition.
The program must decode the uuencoded data before displaying or extracting the archive contents.
A .uu file is an encoding of archive data rather than a modern archive format for general use. Decode it first with a uuencode-compatible tool, then extract the resulting archive.
WinZip can decode and repack the contents in another archive format where supported. Conversion changes the archive after decoding; it does not convert the ASCII encoding directly.
Englishtext/x-uuencode
Software applications that can open uu files:
Apple macOS / Mac OS X
Software apps that extract uu files:
Apple macOS / Mac OS X
