As a developer on 1upHealth, you can connect your application to data from multiple health systems. All you need to do is direct your users via the 1upHealth connect API and have them OAuth via their patient portal credentials.
For testing purposes EHR vendors have made these test username and passwords available. In our application, the demo connection health systems will be accompanied by the text
Test Allscripts EHR ID:
Test Cerner EHR ID:
Test Medicare EHR ID:
Test eCW EHR ID:
If you have not already created a developer account here's the link to sign up free.