How to obtain your reminders and timers in JSON format?
How Your Data Is Stored
Your reminders and timers are stored in a file with the extension .duedb. It is a machine-readable JSON file, compressed with gzip.
Obtaining Your Data In JSON Format
To obtain a copy of this file, you can go to Finder > Go > Go To Folder… and key in ~/Library/Containers/com.phocusllp.duemac/Data/Library/Application Support/Due App/
You can then copy the file named Due.duedb to a location of your choice, rename the file with the extension .json.gz, decompress the file by opening it to obtain the file in JSON format.
Be sure not to move or modify the original Due.duedb file, which will cause Due to malfunction.