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What is libvim?

libvim is a fork of Vim, with the goal of providing a minimal C-based API, modelling Vim modal editing. It does not include any user interface at all (not even a terminal UI), and is primarily responsible for acting as a fast buffer manipulation engine, faithful to Vim keystrokes. It's still a work-in-progress and there is lots of work left to stabilize.

If you're looking for a terminal Vim, check out neovim, or a GUI Vim, check out Onivim 2.


libvim is primarily intended for Onivim 2. After implementing several iterations of 'UI Vims' between v1, v2, and other projects, the abstraction I wished to have was a sort of a pure functional Vim, completely decoupled from terminal UI - where 'vim' is a function of (editor state, input) => (new editor state). As Onivim 2 completely handles the rendering layer, this Vim-modelled-as-a-pure-function could focus on just buffer manipulation.

To that end, libvim exposes a simple C API for working with Vim, and supports listening to buffer changes, messages, etc.

It is responsible for:

  • Managing and manipulating buffers
  • Buffer manipulation in response to input
  • Parsing and sourcing VimL
  • Handling key remaps

It is NOT responsible for:

  • Any sort of UI rendering (terminal, etc)
  • Mouse support
  • Syntax Highlighting
  • Spell Checking
  • Terminal Support
  • Completion
  • Input methods (IME)

All of these are intended to be handled by the consumer of the library - leaving libvim to be focused on the job of fast buffer manipulation.

libvim builds cross-platform (since Onivim 2 requires it!), as well as for WebAssembly - we'd like to port our v1 tutorials to a browser-based experience.

There are other interesting applications of such an 'abstracted Vim':

  • WebAssembly builds could be useful for implementing Vim modes in browsers / websites
  • Native builds could be useful for applications that want Vim-native bindings - it'd be a nice foundation for implementing readline, for example.


For an example of the API usage, check out the apitests like normal_mode_motion. The full API is available here: libvim.h

The heart of the API is vimInput which takes a single key, and is synchronously processed by the state machine. 'Side-effects' like buffer updates, messages, etc can be subscribed to via callbacks like vimSetBufferUpdateCallback.

This library is in active development and we currently make no guarantees about backwards compatibility. Use the API at your own risk.



Install WSL (Windows Subsystem for Linux), and from there, do:

sudo apt install gcc-mingw-w64-x86-64
cd src

Linux or Mac OS

cd src


If libvim is interesting to you, and you'd like to support development, consider the following:


If you would like to help making libvim better, see the file.

Some places for contribution:


libvim code is licensed under the MIT License.

It also depends on third-party code, notably Vim, but also others - see ThirdPartyLicenses.txt for license details.


libvim: The core Vim editing engine as a minimal C library







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