All about UU Files

The UU file type is primarily associated with uudecode.

UU	File extension: UU
	File type:	encoded file

What is a UU file?

UU files mostly belong to uudecode. UU files are text files produced by the uuencode process. They convert binary data into plain text so that the files can be transferred over systems that do not handle raw binary well.
Once received, these files must be decoded to restore the original content. The original data can be of many types. For example:

PDF documents that have been encoded for safe transfer.

Archive files such as RAR and ZIP; decoding reveals the original archive. Tools like WinRAR for RAR or Microsoft Word for ZIP-based archives may then open the file.

Media files including MP4 videos and JPG images. Programs such as ffmpeg or Adobe Photoshop (for images) work with such data after decoding.

Files holding web page snapshots, JSON text, plist data, or even macOS executables; additional details can be reviewed on resources like Blink or in the RFC documents.

Audio files encoded in formats like Ogg; more information is available on Wikipedia: Uuencoding.

FilExt.com note: The decoding step, often performed with utilities such as uudecode or uudeview, restores the file to its original binary state. This method was common on Unix systems and remains in use for transferring files through email or newsgroups where only text is allowed.

How to open UU files

You need a suitable software like uudecode to open a UU file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your UU file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a UU file directly in the browser:. Just drag the file onto this browser window and drop it.

Online UU Text Viewer

Choose your .uu file to analyze

or drag and drop it here

Online File Viewer

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UU file format details:

Each file has a definite file format, that is, how the stored data is arranged in the file. The file format can be deduced from the file extension and the signature. File extension, signature and file format must match; otherwise errors will occur when the file is opened. If there are problems opening a file, you must first determine the file format used. Our evaluation of the UU files is as follows:

The UU extension is very commonly used. This UU file itself is among the most popular common file types and includes very many different file formats. The following file formats are most commonly found in UU files:

• 15% of all UU files internally utilize the PDF file format. PDF is short for Portable Document Format, is a file format to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. These are binary files, so they do not contain words or text. UU files are between 69 KB and 10 MB in size. The file type is very recent. Files like these are about document, and have often person-related content.
• 8% of all UU files internally utilize the RAR file format. RAR is a proprietary archive file format that supports data compression, error correction and file spanning. These files contain neither text nor words, but only data. Most of these files are 37 KB to 1 MB in size. The files contain the following words: Rar!. The file name Transaction advice_MT103 swift DBE3S2009225731090.uu or Transaction adviceMT103 swift DBE3S2009225731090.uu is characteristic of these files. These files are attributed to transaction, swift, advice, confirmation, booking and advicemt.

The remaining 77% of all UU files are files with no common format, frequently e.g. UUencoded/XXencoded text, MP4, Ogg, ZIP, MHTML, JPG, HTML, PNG, ELF, KEY, PSD and JSON. Often described as server, config, macos, apple, list, notification, certificate, maintenance, deemix, output, photo, trace, docx or temp. If you want to find out what your UU file contains, drag and drop it onto this page.