This is likely because your system doesn't have OpenGL support. TL;DR:

Download mesa-llvmpipe-x64-24.3.4.zip and put opengl32.dll in the same folder as Picocrypt.exe. Relaunch and it should work.

Full details

Picocrypt's GUI library, giu, uses Dear ImGui under the hood which relies on OpenGL 3.2, a graphics API, to draw its UI. On Windows, as of the time of writing (2025), all three major vendors (Intel, AMD, Nvidia) have full OpenGL 3.2 support in their drivers, however, this may change in the future as other layers like DirectX 12 or Vulkan become more popular, or maybe you're running Windows in a VM or Windows on ARM. If so, you'll need a software OpenGL 3.2 renderer to "emulate" a native driver. Fortunately, the amazing open-source Mesa project provides llvmpipe which does just that: it allows you to get OpenGL 3.2 support on systems without a driver using just the CPU, aka it'll run on any Windows environment. Linked above for easy access is a build of llvmpipe into opengl32.dll which by placing beside Picocrypt.exe, will be used instead of the system's (potentially nonexistent) opengl32.dll due to the lookup rules of LoadLibraryA. To Picocrypt, it looks like OpenGL 3.2 is supported, and llvmpipe will "emulate" support for it. This should allow you to run Picocrypt on Windows where it didn't run before. If it still doesn't launch, well, your system is just weird :)

To get the latest llvmpipe builds from their source, please check out:

1. https://github.com/mmozeiko/build-mesa (recommended)
2. https://github.com/pal1000/mesa-dist-win