Valuable services support many variations in clients, such as mobile versus web and different forms of web interface. It’s tempting to design a single back-end API to support all clients with a reusable API. But client needs vary, as do constraints such as bandwidth for mobile devices versus the desire for lots of data on fast web connections. Consequently it’s often best to define different back-end services for each kind of front-end client. These back ends should be developed by teams aligned with each front end to ensure that each back end properly meets the needs of its client.