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Cross-platform IDE for Piet.


Pietron is a cross-platform IDE for editing and debugging the source code of "Piet", an esoteric programming language.

The specification of Piet is here.

Pietron is developed with Electron and named after it.




  • Draw free lines by dragging on the canvas.

  • Select a color by clicking on the palette and the selected is shown at the bottom-right corner.

  • Change the color to draw with by clicking on the palette.

    • The commands are shown in each color on the palette.

    • The bare one is from * (origin) and the parenthesized one is to *.

    • Change the * color by right-cicking on the palette.

  • Pick a color by right-clicking on the canvas.

  • Change the canvas size in various ways.

    • Change the canvas size one by one with the top-left position fixed with Ctrl + Alt + [↑↓←→] (⌥⌘ on OSX).

      meaning keyboard shortcut
      extend to the right Ctrl + Alt + →
      extend downwards Ctrl + Alt + ↓
      trim the rightmost column Ctrl + Alt + ←
      trim the bottom row Ctrl + Alt + ↑
    • Change the canvas size one by one with the bottom-right position fixed with Ctrl + Shift + [↑↓←→] (⇧⌘ on OSX).

      meaning keyboard shortcut
      shift the image to the right Ctrl + Shift + →
      shift the image down Ctrl + Shift + ↓
      trim the leftmost column Ctrl + Shift + ←
      trim the top row Ctrl + Shift + ↑
    • Change the canvas size to the specified width and height with Ctrl(⌘) + R.

  • Undo/Redo support (Ctrl(⌘) + Z / Ctrl + Y (⇧⌘Z)).

  • Zoom support (Ctrl(⌘) + ";" / Ctrl(⌘) + "-").


  • "Start Debug" executes commands until the program terminates (F5).

    • When the commands are executed over 1,000,000 times, a comfirmation dialog will be displayed.
  • "Jump Debug" excutes the specified number of commands (F6).

  • "Step Debug" excutes a next command (F7).

  • "Stop Debug" stops the execution (ESC).

  • While debugging, the source codel and the destination codel are indicated by red and blue borders.

  • 🎨Emoji🐛 Support.

File I/O

  • PNG/BMP support.

  • Codel size specification support.

  • Non piet colors are dealed as white.


Download zipped files for your operating system from releases.

Executable files are contained in them.


  • dnek - Piet lover - dnek


This project is licensed under the MIT License - see the LICENSE file for details.


  • Canvas with HTML5 <canvas>.

  • Editor Selection mode.

  • Move with arrow keys on the canvas.

  • Command preview on the canvas.

  • Breakpoint.

  • File drag & drop.

  • Set the limits of stack & integer.

  • Debug log.


  • Pidet is my previous product and I do not recommend using it.

    • Japanese only.

    • Windows support only.

    • No Emoji support.

    • Not maintained.