.KV File Extension

There is only one file type that uses the .KV extension:

Kivy Language File

Kivy Language File

A KV file is a Kivy language file created by Kivy, an open-source Python library used to develop multi-touch enabled, cross-platform applications. It stores source code in the Kivy syntax, which may include rule definitions, a root widget, dynamic class definitions, and templates.

Kivy is a framework that assists developers in creating cross-platform apps with Python code. It is specifically focused on describing the user interface and interactions in an app.

The Kivy language features several constructs:

  • Root widget - Widgets are the building blocks of GUIs in Kivy and a KV file can contain only one root widget.
  • Rules - A Kivy rule applies to a specific widget and is used in a KV file to modify the widget, such as specifying interactive behavior or adding a graphical representation of a widget.
  • Dynamic classes - A Kivy dynamic class allows you to quickly create new widgets or rules without any Python declaration.
  • Templates - Before being deprecated, Kivy templates were used to save the user time when styling content, like only having to specify the value of a button once for buttons that are used repeatedly. Templates were replaced by dynamic classes in version 1.7.0 of Kivy.

Below is a simple example of a KV file containing a root widget. A KV file should always start with the Kivy header, with the correct Kivy language version used, and then followed by the content:

#:kivy 1.11.1

      text: 'Hi there'

You can open KV files with Kivy, which is free and available for Windows, macOS, Linux, Android, and iOS. You can edit KV files with JetBrains PyCharm (multiplatform), a Python IDE and Microsoft Visual Studio Code (multiplatform), a source code editor.

Since KV files are saved in plain text, you can also open and edit KV files with a plain text editor, such as Microsoft Notepad (bundled with Windows) or Apple TextEdit (bundled with macOS). However, these text editors do not provide helpful source code editing features.

Software's name License Platforms
Any text editor Any text editor AndroidChrome OSiOSLinuxMacWindowsWindows Phone
JetBrains PyCharm JetBrains PyCharm Free LinuxMacWindows
Kivy Kivy Free AndroidiOSLinuxMacWindows
Microsoft Visual Studio Code Microsoft Visual Studio Code Open Source LinuxMacWindows

Updated: May 25, 2021

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