Good morning,

we use Pulseway for our customers, they are then billed by us per server and per client.
Is there an easy way to see which customer has how many servers and how many clients?

Systems - Groups - Look at the total in the group assuming you have them set up as each client is a group/organization.

Account - Manage Systems - Download CSV, Sort, Sum them.

Server Admin - Configuration - Click Organziation/Group - Show Systems

Or use API to make your own quick report.