The file needs to be in the .txt format
Thanks a lot to Jasmine for the gd-level-to-json library on github
1. Open GDColon's website here.
2. Follow your device-specific instructions below.
3. Locate the level you want to be converted.
4. View the level data of the level (inner string) and create a .txt file of it.
5. Drag the .txt here.
Instructions for Windows:
1. Press WIN + R.
2. Type in "%localappdata%/GeometryDash".
3. Drag the CCLocalLevels.dat file into the box.
Instructions for Mac:
1. Locate ~/Library/Application Support/GeometryDash.
2. Drag the CCLocalLevels.dat file into the box.