Code and data file formats
67 formats in this category.
Code and data formats are almost always plain text. They are meant to be read by both people and programs, which is why most open instantly in any text editor.
Plain text, read by people and machines
Code and data-interchange formats are almost always plain text, which is why they open instantly in any editor and show up cleanly in version control. Source files (JavaScript, HTML, CSS, Python and the like) are instructions for a program or a runtime. Structured-data files (JSON, XML, YAML, CSV) carry information in a shape both humans and programs can read. Config files (INI, TOML, and many dotfiles) tell software how to behave.
Because they are text, the extension is a convention rather than a hard requirement: a .json file is just text that happens to follow JSON syntax. Editors and linters use the extension to pick the right highlighting and validation.
Encoding and line endings
Two invisible details cause most cross-platform headaches with text files: character encoding and line endings. UTF-8 is the modern default and handles every language; older files may use other encodings and show garbled characters. Windows ends lines with a carriage return and line feed (CRLF) while Unix uses a line feed alone (LF), which is why a file can look single-lined when opened in the wrong editor.