@matt When I try the API call, it works. It gives me back a very large JSON file. You might need to tell your code to save the response to disk. There is an alternative though. If you log in to the Tado website, then open your browser's developer tools, and switch to the "network" tab - you should be able to see all the API calls that Tado makes. Open the Heating option and click on the graph. You should see today's data. Look in the network tab and you'll see the API call your browser makes. You can either copy the API call from there, or save the response to disk.

Good luck!