CONF File

What are CONF files and how to open them

Are you having problems opening a CONF file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CONF files.

What is a CONF file?

CONF files have multiple uses, and Configuration is one of them. Read more about the other uses further down the page.

Configuration File

Files that contain the .conf file extension are configuration files that are used to store the configuration and settings for a variety of different computer processes and applications. These files are usually written in plain text and used for user applications, operating system settings and server processes.

CONF files are commonly used in Unix and Linux operating systems. Most CONF files are saved in text file format. In some cases, if a user wants to modify the settings of an application that is being used on a computer that is running on Linux or Unix, they must modify the CONF file in order to do so.

How to open CONF files

We have identified three CONF openers that are compatible with this specific type of CONF file.

Programs that open Configuration files

Last updated: September 2, 2026

All known file formats using extension .CONF

While Configuration File is a popular type of CONF-file, we know of 7 different uses of the .CONF file extension. Different software may use files with the same extension for different types of data.

DOSBox Configuration

The DOSBox Configuration format is a plain‐text settings file used by the DOSBox emulator to define how an emulated system behaves. It controls display, sound, input devices, memory, CPU speed, machine type, serial ports, mounted drives, and other system parameters. This file is written once - either globally or per‐game - and then read by DOSBox to set up the environment before launching DOS applications. It allows users to fine‐tune how hardware is emulated so that older software runs correctly.

DOSBox writes this configuration file automatically on first launch (usually in the user profile or home directory), provides a default version, and allows multiple versions to coexist. Users often make game‐specific copies to adjust settings like CPU cycles or graphics mode uniquely per game. The file also defines a special section (named autoexec) whose lines are executed as DOS‐commands after initialization, for example mounting directories or starting programs. Settings can also be modified at runtime via the built‐in CONFIG tool, which can write out a new configuration file or apply individual property changes.

Inside, the file is divided into sections marked by lines like [sdl], [dosbox], [cpu], [dos], [ipx], [autoexec], etc. Within each section are property=value lines, where values choose from ranges (true/false, numeric, named machine types, etc.). Comment lines begin with # (or sometimes %) and are ignored. Common options include fullscreen, output (graphics backend), memsize, machine type, cycles, key mapping files, joystick/sound settings, CPU type, and drive mounting commands.

Files of this format begin with identifiable signatures. A typical DOSBox configuration file starts with "[sdl]" at the very beginning (byte offset 0), and includes keywords like WINDOWRESOLUTION, FULLRESOLUTION, KEYBOARDLAYOUT, JOYSTICKTYPE, MAPPERFILE, MACHINE, MEMSIZE, and AUTOEXEC among others.

While we have not verified the apps ourselves yet, our users have suggested ten different CONF openers which you will find listed below.

Fontconfig Configuration

Fontconfig Configuration files are used by the fontconfig library to define how system or user fonts are discovered, matched, aliased, cached, and modified. These files are written by system maintainers, packaging scripts, or by fontconfig itself, and they instruct the fontconfig library - used by graphical environments on Unix-like systems - on how to load font directories, remap font families, set cache locations, and apply matching rules.

The library that reads these files is fontconfig. Applications that need to select or render fonts ask fontconfig to give them fonts matching certain patterns, and fontconfig uses its compiled configuration to perform matching, filtering, aliasing, and other tasks. Fontconfig parses all available configuration files (usually in system-wide directories like /etc/fonts/ and per-user directories under ~/.config/fontconfig/) to build an internal representation which it uses at runtime. This representation remains loaded and is shared across applications to ensure consistent font behavior.

Fontconfig configuration files are XML documents that must conform to a document type definition called fonts.dtd. They begin with an XML declaration, followed by a DOCTYPE declaration referencing the "fontconfig" root element and the fonts.dtd. The content inside the top-level <fontconfig> element may include child elements such as <dir>, <cachedir>, <include>, <config>, <match>, and <alias>, in any order. These child elements define font search paths (<dir>), location(s) for cache files (<cachedir>), other configuration files to include (<include>), global parameters like blank glyph handling or rescanning (<config>), rules to match font pattern properties (<match>/<test>/<edit>), and aliasing of font family names. Text values like directory paths or family names appear inside elements such as <string>, <const>, or <name>. An example signature appears at the very start of the file: the byte sequence corresponding to "<?xml version="1.0"?><!DOCTYPE fontconfig SYSTEM …>", and strings like "DOCTYPE FONTCONFIG SYSTEM" or "FONTS.DTD" occur near the beginning so that parsers or format detectors can identify the file.

Fswebcam Configuration File

Fswebcam configuration files set up how the fswebcam tool captures images from video devices, formats them, and optionally adds banners, overlays or executes commands. These files are written as plain text and are read by fswebcam at startup or when launched with the --config option. They let users store commonly used settings so that every capture need not be invoked with multiple command-line arguments.

Options in a configuration file mirror fswebcam's long-form command-line switches but omit the leading "--" prefix. Lines beginning with "#" are comments. Key settings include selecting the video device (often under /dev/video0), specifying resolution (e.g. 768x576), defining how many frames to capture or skip, setting frame rate and format (JPEG, PNG, WEBP), and positioning a banner (top or bottom). Text elements like title, subtitle, timestamp, and info may be configured, along with colours for banner-background, line, and text. Overlay and underlay PNG images may also be included. Executable commands can be run after capture, for example to move or archive files.

Configuration files accept colour values in web-style hexadecimal form, which may include an alpha (transparency) channel (#AARRGGBB). Fonts can be specified either as font files or by font name, optionally with a size; default settings are used if not set explicitly. Other settings cover verbosity (quiet mode), saving output, scaling images, and skipping initial frames to avoid bad-startup artifacts.

Technical identifier: files typically begin with a comment line like "# Example configuration for fswebcam" or "# CONFIGURATION FOR FSWEBCAM", include keywords such as DEVICE, RESOLUTION, SAVE, EXEC, QUIET, BANNER-COLOUR, LINE-COLOUR, TOP-BANNER, FONT, SCALE, JPEG or PNG, and may reference the default video input "video0".

Geany Theme File

Geany theme files store color schemes that define how the Geany text editor displays code syntax, interface elements, and other styled text. These files let theme authors set colors, text styles (like bold or italic), and which Geany versions a theme works with. Geany itself reads these files to let users pick different visual styles for the editor.

Files of this format are created and maintained in the geany-themes project, a repository of themes compatible with Geany. The themes are saved by developers or community contributors as plain text INI-style files in a special "colorschemes" folder. Users install them by placing them into Geany's colorschemes directory, after which Geany discovers them, and users can switch between themes using the View → Change Color Scheme menu.

Each theme configuration file is divided into named sections. The [theme_info] section includes metadata: theme name, author, version, a description, a URL, and compatible Geany versions. The optional [named_colors] section defines reusable color definitions. The main styling section (often [named_styles]) assigns colors and text formatting per category (such as keywords, strings, comments). Each style is set using a line where a category equals a specification of foreground color, background color, and flags for bold and italic. For example: keyword=#BF4D58;#1e1e1e;true;false means keyword text is colored in the hex color #BF4D58, on background #1e1e1e, displayed as bold, not italic. Aliases are allowed: a style line can refer to another defined style name.

Internally the file uses INI formatting: sections marked by square brackets; key=value pairs under each section. Color codes use hexadecimal RGB notation starting with #RRGGBB. Boolean fields are expressed as true or false. Some entries may leave background blank to inherit default background. The version field in [theme_info] is auto-incremented by build tools when the theme changes.

Hydrogen Drum Machine Configuration File

Hydrogen Drum Machine Configuration File stores the preferences and settings for Hydrogen, an open-source drum sequencer and drum machine. It is created by Hydrogen when a user changes options in the Preferences dialog, and is read by Hydrogen on startup to restore audio driver, interface layout, editor behavior, theme properties, and other prior state.

Settings in this file include choice of audio and MIDI/OSC drivers, sample rate, buffer size, whether to restore last song, quantization, appearance options such as font size and colors, grid resolution in editors, recent files lists, and more. The file influences how various parts of Hydrogen appear and behave, including pattern editor, song editor, mixer, main window layout, JACK or ALSA settings, etc. It does not define drumkits, song content, or actual audio samples.

The file is XML format: an XML document whose root element is "hydrogen_preferences" or "Hydrogen Preferences". Individual settings appear as child elements named for each preference, such as "version", "restoreLastSong", "useTimeLine", "path_to_rubberband", etc. Certain nested elements represent lists - e.g. "recentUsedSongs" contains multiple "song" child elements. The file begins with a signature like <hydrogen_preferences> (bytes 0x3C687964726F67656E5F707265666572656E6365733E at offset 0) and contains keywords such as SONGEDITOR_COLORINGMETHOD, PATTERNEDITOR_GRID_RESOLUTION, JACK_TRANSPORT_MODE_MASTER, APPLICATION_FONT_POINTSIZE, and many others.

Psitree Router Configuration File

We know that one CONF format is Psitree Router Configuration File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Various apps that use files with this extension

These apps are known to open certain types of CONF files. Remember, different programs may use CONF files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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