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The Open Toolkit library is a fast, low-level C# binding for OpenGL, OpenGL ES and OpenAL. It runs on all major platforms and powers hundreds of apps, games and scientific research.

Use OpenTK to add cross-platform 3d graphics, audio, compute and haptics to your C# application. Integrate it into your existing user interface or use it standalone without any external dependencies.

Project website:

Official git repository:


  • Create cutting-edge graphics with OpenGL 4.4 and OpenGL ES 3.0
  • Spice up your GUI with 3d acceleration
  • Improve your code flow with strong types and inline documentation
  • Write once run everywhere

OpenTK is available for Windows, Linux, Mac OS X, *BSD, SteamOS, Android and iOS. It can be used standalone or integrated into a GUI (Windows.Forms, WPF, GTK+, Qt, VTK, ...)

Download binaries or NuGet packages


The simplest way to use OpenTK in your project is to install the NuGet package.

Alternatively, download the OpenTK binaries and:

  1. Copy OpenTK.dll and OpenTK.dll.config to your project directory
  2. Use "Add reference" to add OpenTK.dll as a project reference
  3. Use "Add files" to add OpenTK.dll.config to your project, and enable the "Copy to Output Directory" option.

To build OpenTK from source, simply double-click OpenTK.sln and build through your IDE.

Alternatively, open a command prompt and type: git clone # Download source code from git cd opentk # Enter the source directory msbuild /p:Configuration=Release OpenTK.sln # Build on .Net (Windows) xbuild /p:Configuration=Release OpenTK.sln # Build on Mono (Linux / Mac OS X)


OpenTK 1.1.4c was released on 24 July 2014.

This is a hotfix release that improves stability on Mac OS X. Moreover, it synchronizes the GamePad configuration database with SDL 2.0.4 and fixes an invalid GUID introduced in 1.1.4b.

OpenTK 1.1.4 was released on 21 July 2014.

This release resolves a number of identified issues, adds experimental support for Linux/KMS and synchronizes the OpenGL and OpenGL ES bindings with the July 2014 Khronos specifications.


  1. Fixed a memory leak in OpenGL functions accepting a string array.
  2. Fixed an issue where MakeCurrent() might fail on Linux/X11 when using the Nvidia closed-source drivers.
  3. Fixed an issue where GameWindow might remain open on Linux/X11 after calling Close() or Dispose().
  4. Fixed a potential crash on Mac OS X systems without hardware acceleration (e.g. virtual machines).
  5. Fixed function parameters for the OES_byte_coordinates extension.
  6. Fixed an issue where OpenTK would always perform a full rebuild even when a partial rebuild could work.
  7. Fixed all compilation warnings on VS2013 and Mono 3.4.0.
  8. Improved OpenGL and OpenGL ES documentation on 'count' parameters.
  9. New platform: Linux/KMS. You can now run OpenTK applications on a Linux terminal without an X11 display server.
  10. New OpenGL ES extensions:
  11. ANDROID_extension_pack_es31a

OpenTK 1.1.4 is backwards compatible with 1.1.3. Users of previous versions are strongly encouraged to upgrade.

Known issues

  1. The SDL2 backend has a number of limitations compared to the native platform backends. In particular, SDL2 does not support:
  2. OpenTK.GLControl. OpenTK will automatically switch to a native platform backend instead.
  3. DisplayDevice.ChangeResolution() without a fullscreen INativeWindow.
  4. Switching between WindowBorder.Fixed and WindowBorder.Resizable.
  5. High-resolution mouse input. Additionally, it is limited to a single keyboard and mouse device.
  6. OpenTK.Input.GamePad.SetVibration is currently not implemented. This API will be implemented in a future release.


  1. Install git and a C# IDE (see requirements section below)
  2. Fork the develop branch of
  3. Commit your changes in small, incremental steps with clear descriptions
  4. When ready, issue a Pull Request (PR) against the develop branch of

For details on coding style and best practices, refer to

Some areas we could really use your help: - Tutorials for OpenGL 3.x and 4.x. Inspiration here - New platforms: - Native Client (NaCL) - Blackberry - Wayland - Mir - WinRT (via ANGLE) - New features: - Multitouch - Force feedback - Improved joystick support (HID backend for Windows, Linux)

Further ideas for improvement are always welcome!


  • Windows (XP/Vista/7/8), Linux, Mac OS X, *BSD, SteamOS, Android or iOS
  • For graphics, OpenGL drivers or a suitable emulator, such as ANGLE
  • For audio, OpenAL drivers or OpenAL Soft
  • To develop desktop applications: Visual Studio, Xamarin Studio, MonoDevelop or SharpDevelop
  • To develop Android applications: Xamarin Studio or the Xamarin Extensions for Visual Studio
  • To develop iOS applications: Xamarin Studio and XCode


Your favorite IDE will display inline documentation for all OpenTK APIs. Additional information can be found in the OpenTK Manual and in the opentk/Documentation/ folder.

Technical documentation about the implementation of OpenTK can be found in the Technical Wiki.

Need Help?

Post your questions at the OpenTK forums.

Report bugs at


The Open Toolkit is distributed under the permissive MIT/X11 license and is absolutely free.

API compatibility

OpenTK 1.1.4 is backwards compatible with 1.1.3.

OpenTK 1.1.3 is backwards compatible with 1.1.2.

OpenTK 1.1.2 is backwards compatible with 1.1.1.

OpenTK 1.1.1 is backwards compatible with 1.1.0.

OpenTK 1.1.0 is not backwards compatible with 1.0. Most projects will be able to upgrade without any modifications. Projects using the following signatures will have to implement the suggested changes:

Namespace OpenTK.Graphics.OpenGL Change signature: - GL.MultiDrawArrays (out -> ref) - GL.Amd.DeletePerfMonitors (out -> ref)

Change signature (may cause crash): - GL.Apple.ObjectPurgeable (returns AppleObjectPurgeable instead of IntPtr) - GL.Ext.SeparableFilter2D - GL.Ibm.EdgeFlagPointerList (bool[] -> bool*[]) - GL.NV.TransformFeedbackVaryings (string[] -> int[])

Change return type: - GL.WaitSync (returns WaitSyncFlags instead of ArbSync)

Namespace OpenTK.Graphics.ES11 Change return type: - GL.GetError (ErrorCode instead of All)

Change ref parameters to out: - GL.GenBuffers - GL.GenTextures - GL.GetBoolean - GL.GetBufferParameter - GL.GetClipPlane - GL.GetClipPlanex - GL.GetFixed - GL.GetFloat - GL.GetInteger - GL.GetLight - GL.GetLightx - GL.GetMaterial - GL.GetMaterialx - GL.GetTexEnv - GL.GetTexEnvx - GL.GetTexParameter - GL.GetTexParameterx - GL.Oes.GenFramebuffers - GL.Oes.GetClipPlane - GL.Oes.GetClipPlanex - GL.Oes.GetFixed - GL.Oes.GetFramebufferAttachmentParameter - GL.Oes.GetLightx - GL.Oes.GetMaterialx - GL.Oes.GetRenderbufferParameter - GL.Oes.GetTexEnvx - GL.Oes.GetTexGen - GL.Oes.GetTexGenx - GL.Oes.GetTexParameterx - GL.Oes.QueryMatrixx - GL.NV.GenFences - GL.NV.GetFence

Change namespace: - GL.ClipPlanefIMG -> GL.Img.ClipPlane - GL.DisableDriverControlQCOM -> GL.Qcom.DisableDriverControl

Namespace OpenTK.Graphics.ES20.GL Change signature (may cause crash): - GL.NV.GetFence now takes three parameters instead of two

Change ref parameters to out: - GL.GetActiveAttrib - GL.GetActiveUniform - GL.GetAttachedShaders - GL.GetProgramInfoLog - GL.GetShaderInfoLog - GL.GetShaderSource - GL.Amd.GetPerfMonitorCounterData - GL.Amd.GetPerfMonitorCounters - GL.Amd.GetPerfMonitorCounterString - GL.Amd.GetPerfMonitorGroup - GL.Amd.GetPerfMonitorGroupString - GL.Amd.SelectPerfMonitorCounters

Change namespace: - GL.DisableDriverControlQCOM -> GL.Qcom.DisableDriverControl - GL.GetDriverControlsQCOM -> GL.Qcom.GetDriverControls - GL.GetDriverControlStringQCOM -> GL.Qcom.GetDriverControlString

See also

Delta Engine, a high-level, open-source game engine. MonoGame, an open-source, cross-platform implementation of XNA.

Source:, updated 2014-07-23