Hello! So you want to take your Exist data and do interesting things with it. Great! First things first, though: the API can only be accessed by user accounts. Sign up if you don't yet have an account. Once you do, great! You can access all features of the API including writing data to attributes.
If you're building something on the Exist API we encourage you to sign up to the API mailing list so we can update you on any changes (typically we only email a few times a year). You can also chat with other developers and see what the community has made in our forum.
From here you can:
You can also still access the docs for the deprecated v1 API.