Want to dive right in?
The xumm platform allows developers and app users to "meet up". While users can simply use the xumm app to track their accounts, balances and transactions, the true power of xumm is the platform that is made available to developers and their applications for end-users.
For an introduction, see: Introduction (Guide)
Please note that, instead of calling the XUMM API yourself, you can use the XUMM SDK instead. Here's a tutorial.
The SDK accepts input & returns output in JSON as documented here.
Please read the Payload workflow guide before implementing the xumm API in your application.