This is a list of computer file formats, categorized by domain. Some formats are listed under multiple categories. Most of the file endings are traditionally written lower case, at least on Linux/Unix, such as .gz, .class, and very often on Windows too, e.g. .exe (though historically only upper case .EXE as in DOS). Windows is case insensitive (unlike many other systems) so you can not have a file name duplicated with same or even different content, with e.g. the ending in a different case, but you could e.g. on Linux, with e.g. with different file with .CLASS ending with different content, so it's good there to standardize endings on lower case.

Each format is identified by a capitalized word that is the format's full or abbreviated name. The typical file name extension used for a format is included in parentheses if it differs from the identifier, ignoring case.

The use of file name extension varies by operating system and file system. Some older file systems, such as File Allocation Table (FAT), limited an extension to 3 characters but modern systems do not. Microsoft operating systems (i.e. MS-DOS and Windows) depend more on the extension to associate contextual and semantic meaning to a file than Unix-based systems.

Computer-aided is a prefix for several categories of tools (e.g., design, manufacture, engineering) which assist professionals in their respective fields (e.g., machining, architecture, schematics).

Computer-aided design (CAD) software assists engineers, architects and other design professionals in project design.

Electronic design automation (EDA), or electronic computer-aided design (ECAD), is specific to the field of electrical engineering.

Files output from Automatic Test Equipment or post-processed from such.

These files store formatted text and plain text.