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.
You might also be looking for the JSON from the next LDtk version (1.4.0).
The JSON format evolves on each app update. Sometimes, this means removing some values that are no longer relevant.
The following listing shows these values. If you're working on your own JSON parser, please make sure to update your code before this happens.
Learn more about deprecations rules in the documentation.