Hello!
Our backed using couchbase is not ready yet, while mobile applications can implement it now.
Is there some test API from couchbase to test mobile applications syncing and then just switch endpoint?
You can definitely set up a couchbase server and a sync gateway service, and test your mobile app by pointing to the sync gateway service url when you configure the replicator. When the backend couchbase server and sync gateway are ready to use, then you can simply to update the sync gateway service url in your mobile app, or when you design your mobile app, make the service url to be configurable in order to switch in between backend environments.
Here are the documentation for how to set install sync gateway and couchbase server, you can have VMs or docker to set them up:
https://docs.couchbase.com/sync-gateway/2.7/index.html
https://docs.couchbase.com/server/6.5/install/install-intro.html
To add to what Eunice said here is the code sample on the app side
It looks like you are looking for a hosted Couchbase Server/ Sync Gateway service for your app’s testing purposes - no, we don’t have one . You will have to set up couchbase server, sync gateway yourself (which you can do locally on your laptop and as pointed to in the other responses, there are several options ).