What is the CFG file format?
A .cfg file contains configuration settings for an application or program. .cfg is a generic configuration file that stores information required by a given piece of software to function properly. Files can hold data in plain text or binary format, and some applications also use encryption. Usually .cfg files hold custom settings, and can refer to an application as a whole or focus on only a subset of configuration parameters.
Because no single standard governs the extension, the internal structure is entirely application-defined. Most .cfg files are plain text and follow either a simple key=value pattern or an INI-style layout - [SectionName] headers grouping name=value pairs beneath them. On Unix and Linux systems, the same role is often filled by .conf files. Some specialized programs (certain CAD suites, game engines, or hardware utilities) produce .cfg files in a proprietary binary format; those appear as garbled text in an editor, and the originating application is needed to read them correctly.
.cfg files are typically saved in text format and can therefore be edited with any plain-text editor. They should be modified with caution, as errors can cause the related application to misbehave or refuse to start. Some programs require a .cfg file to be present, while with others such a file is optional. If no .cfg file is found, the program will use its built-in default settings.
A .cfg file can contain:
- A list of parameters and their values
- References to other files or directory paths
- Section headers grouping related settings
- Embedded parameters with values that can be overridden at runtime
In the case of .cfg files for workspaces or computer games, such files are commonly shared among users over the internet. .cfg files can be generated automatically by changing settings within the application, using dedicated configuration-generating tools, or written manually by the user.
Security & safety
RISK: MEDIUMA text .cfg is safe to open and read. The risk is in EDITING: because a .cfg often controls whether its program starts and how it behaves, a bad value, typo, or wrong line ending can break the application or, for device configs, knock a router offline. Always copy the original to a backup before changing anything, edit with a plain-text/code editor (never a word processor that adds formatting), and change one thing at a time. Also be wary of downloaded "optimized" .cfg files for games or hardware from untrusted sources - a config can point a program at malicious paths or settings; only use configs from sources you trust.
Format details
in a nutshellPrograms that open CFG files
Windows4 apps
Windows Notepad
Built-in Right-click > Open with > Notepad for quick edits. Fine for small text .cfg files; lacks syntax help. 
Notepad
Open-source Right-click > Edit with Notepad++; it shows line numbers and syntax for safe editing. Best free choice for text .cfg files. 
Visual Studio Code
Free Open the .cfg to read/edit with bracket and INI highlighting. Good for larger or structured config files. 
Notepad2 / Notepad3
Open-source Lightweight Notepad replacement with syntax highlighting; open the .cfg to edit. Notepad3 is the actively maintained fork. 
macOS3 apps
TextEdit
Built-in Open the .cfg, then Format > Make Plain Text before saving so it stays a plain text config (don't save as RTF).
Visual Studio Code
Free Open to edit the config with highlighting; safer than TextEdit for structured files.
MacVim / BBEdit
Open-source Open the .cfg in a code editor for precise editing. BBEdit (free mode) is a popular alternative. 
Linux3 apps
GNOME Text Editor / gedit
Open-source Open the .cfg to read/edit; the default GNOME editor handles config files fine.
nano / vim
Open-source Edit in the terminal: nano file.cfg - standard for server/router config files. Back up first. Technical details
deep spec| Primary encoding | Usually plain text (UTF-8 or ASCII); some applications write .cfg files as proprietary binary |
| Typical syntax styles | Flat key=value pairs or INI-style [SectionName] headers with name=value pairs beneath each section |
| MIME type | text/plain - no dedicated IANA-registered MIME type exists for the generic .cfg extension |
| File signature (magic bytes) | None - .cfg carries no standard header byte sequence; the format is identified by which application created it |
| Comment syntax | Commonly # or ; at the start of a line; the exact token is application-defined |
| Encryption / obfuscation | Supported by some applications; certain game engines and hardware configuration tools store encrypted or obfuscated .cfg files |
| Section support | INI-style variants support one level of [SectionName] grouping; flat key=value files have no section hierarchy |
| File scope | One application may use several .cfg files simultaneously - global, per-user, and per-workspace configs can coexist |
| Runtime reload | Some applications (e.g. game servers) re-read .cfg at runtime and apply changes without a full restart |
| Case sensitivity | Key names are usually case-insensitive for Windows-targeted apps and case-sensitive for Unix/Linux targets |
| Line endings | CRLF on Windows-generated files; LF on Unix/Linux/macOS; most parsers tolerate both |
| Shareability | Game, server, and workspace .cfg files are routinely exchanged between users and published in community repositories |
| Editability | Text-format .cfg files are human-readable and editable in any plain-text editor without special tooling |
| Functional relatives | Serves the same role as .ini, .conf, and .config files - the choice of .cfg extension is purely application convention |
| Released | No single origin - a convention used by software since the early DOS/Windows era |
CFG conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about CFG files.
