Click the "Select File" button above, and choose your 21 file.
You’ll see a preview, if available.
Click the "Convert file to..." button to extract text information.
Convert 21 to another file type
To convert 21 Encrypted files to another format, you need Adobe Acrobat Reader or other Data software.
Convert a file to 21
To convert other file formats to the "Renamed File Archive" file type, you need software like Adobe Acrobat Reader or a similar tool.
About 21 files
The .21 file extension is not a standard, registered file format. Our data analysis shows that it is usually a renamed standard file or a split archive segment. Most commonly, these files are hidden Portable Document Format (.PDF) files, Microsoft Excel (.XLSX) spreadsheets wrapped in a ZIP container, or WhatsApp video media streams (MP4). In severe cases, a .21 file is a standard image (like a JPG) that has been forcefully encrypted by the STOP/Djvu ransomware family. Because the .21 extension is arbitrary, operating systems like Windows and macOS do not assign a default program to it. Double-clicking it will result in an 'App not found' error. This forces users into a frustrating guessing game, trying to find software that can read the data. If the file is encrypted by ransomware, standard conversion will completely fail because the internal data structure is scrambled and unreadable. To restore your data, you must identify the file's true internal structure. The best target formats entirely depend on the hidden data: PDF for documents, XLSX for tabular data, or MP4 for video playback. Standard online converters almost always fail with .21 files because they rely on basic MIME type mapping via the file extension rather than inspecting the internal hexadecimal header. This is a common flaw in automated tools. We read the underlying data structure to determine if it is a safe document, a renamed archive, or corrupted data, allowing you to recover the original file format easily.
Convert.Guru analyzes your 21 file, detects the exact format, and lets you read the text inside.
If you want to convert 21 file to ZIP, RAR, 7Z, TAR, GZ, BZ2, XZ, LZMA, CAB, ACE, ARJ or LHA, you can use Adobe Acrobat Reader or similar software from the "Renamed File or Encrypted Data" category. In the File menu, look for Save As… or Export….
To convert XXE, 7Z, Z, PAK, LHA, DEB, UUE, TAR, LZH, ZIP, PKG or RAR files to 21, try Adobe Acrobat Reader or another comparable tool in the "Renamed File or Encrypted Data" category.
The 21 Converter Story
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our 21 converter.