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SB3 to SB2 Converter

A simple Python 3 program that converts .sb3 files to .sb2 files


  • Python 3 (preferably 3.6.2 or later)


Download and extract the ZIP file and move the file to wherever you want.


  1. Run with Python
  2. Select the SB3 file to open
  3. Click OK to exit. The SB2 file path will be the same as the SB3 file path except for the file extension.

Usage (command line)

  1. Open the terminal or command prompt and navigate to the directory of the file.
  2. Enter the following command: python [unordered options] sb3path [sb2path]
    Options and sb2path are not necessary.
  3. If an error is given, make sure you entered a valid sb3 file.


Options may or may not be separated by a space.
List of options:

  • -h: Displays the program arguments and list of options
  • -c: This enables compatibility mode. Workarounds for the following blocks will be added to sprites:
    • glide to [ v]
    • costume [number v]
    • set drag mode [ v]
    • <[] contains []?> (may result in performance loss)
    • (item # of [] in [ v]) (may result in performance loss)
    • pen color blocks (including HSV and shade blocks)
    • timer blocks
  • -j: Automatically enables compatibility mode and adds an unlimited join workaround (may result in significant performance loss)
  • -l: Automatically enables compatibility mode and adds custom blocks to automatically limit list length to 200,000 (may result in performance loss)
  • -p: Tries to insert blocks to fill the screen when the pen size is set to a value greater than 255

Known Issues

  • MP3 audio files cannot be converted
  • Compatibility mode changes variable monitor labels
  • Compatibility mode allows ([ v] of [ v]) to access only variables (not attributes like x position, backdrop #, etc.)
  • Dragging in projects converted with compatibility mode does not have the same pen behavior as in 3.0
  • Unlimited join does not check case when checking string equality