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Open File – How to Edit and Convert File Extension Formats – Software, Programs and Apps

Welcome to the free online file extension library. This site includes a detailed database, what they are used for, programs they are associated with, and also provides information on how to fix related errors, open and convert files.  

What is the filename extension

The File Extension is an acronym of the type format composed by three or more letters.

The filename is composed by the base name + a suffix with the format that represents the encoding separated by the dot symbol.  


Most Popular File Extension List

These are the most popular formats: 

PDF - Download - ENCFRX - MPGA - CNT - XFL - VCD - SIS - DLL - TMP - RAR - DAT - BAK - XLSX - JPG - DWG - XLS - DOC - BIN - AI MP4 - ZIP - EML - DOCX - 7Z - SWF - PPTX - APK - LNK - CDR - PART - EXE - PNG - Torrent - PSD - DB - WPS - MKV - PHP - CFG - BUP - DMG  - EPS - EMZ - ASPX - DXF - ODS - SHS - STP - DO - MP3 - ODT - SB2 - SIG - LDB - TIF - DJVU - RPT - DBF - CSV - SRT - HEX - PPT - ICA - VOB - P7M - TXT

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Search by letter

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z - Other


The formats have the following types:

  • Audio: Music and audio extensions, .mp3, .wav, .iff, .m3u, .mid, .mpa, .ra, .wma
  • Video: .flv, .avi, .m4v, .mov, .mp4, .mpg, .rm, .mp4, .swf, .vob, .wmv
  • Images: .bmp, .gif, .jpg, .png, .psd, .tga, .thm
  • Text: .doc, .docx, .msg, .odt, .pages, .tex, .txt, .wpd .wps, .pdf
  • Compression: .zip, .rar, .gz, .7z, .tar.gz, .zipx, .pkg



A precise outline of the nature and function of files extensions is surprisingly difficult to define, due to over 40 years of developments in computer hardware and software, and the competing influences of Mac, Windows/Dos, and Unix-like operating systems, each with their own file systems and metadata formats.

The earliest implementation was by Digital Equipment Corporation, during the early 1960s, which then broke a file name into the base name and the suffix. Eventually this convention was adopted by Microsoft’s DOS operating systems and then by Windows.

As a matter of interest, expressing the base name and file extension as a single name, separated by a full stop, was only a convention for showing both pieces of information together. In DOS it was stored separately from the base name. A fact that was in the DOS file manager, where the files extension and the name were in separate columns.

Microsoft originally restricted the base name to eight characters and the file suffix format to a subsequent three characters: for example BASENAME.FEX. This combination of an 8 letter name with a 3 letter file extensions was somewhat restrictive and Windows 95, onwards, allowed longer filenames.

In very simple terms neither UNIX nor Mac operating systems used it. Instead each has had its own file systems, with different conventions for storing metadata, which has changed over time.

UNIX systems would store all the information as a single string. Whilst up until Mac OS X, Apples would store the data using special code contained within the file.

However, acknowledging that the prevalence of Windows has made the files extensions the standard method of expressing a file’s function.

And also reflecting architectural changes to the code made when Mac OS absorbed NeXT Software’s UNIX based OPENSTEP operating system) Mac OS X now uses it as well.