JSON file format (1.1.3)
LDtk saves its data in pure JSON format: a very easy to use standard which is supported by most modern frameworks. You can learn more about the LDtk format in the documentation.
If you don’t want to bother with it, you may also just check if there is any existing API for your game engine in the API section.
You might also be looking for the JSON format in the next LDtk version.