Should every frontend have its own backend?

Not necessarily.

A good rule of thumb is:

• Every frontend needs an API/data source
• But it doesn’t need a completely separate backend

Common patterns

1) One shared backend for many frontends

Example: web app, mobile app, admin panel all use the same backend.

Pros

• Less duplicated logic
• Easier to keep business rules consistent
• Simpler to maintain early on

Cons

• The backend can get too generic
• Different frontends may need different shapes of data
• Changes for one client can affect others

2) Separate backend per frontend

Example: a web frontend has its own backend, mobile has its own backend.

Pros

• Backend can be tailored to each frontend’s needs
• Faster to evolve client-specific features
• Better performance if each client gets custom endpoints

Cons

• More duplication
• More services to maintain
• Business logic can drift or be repeated

3) Shared core backend + frontend-specific BFFs

This is often the best compromise.

• A core backend owns business logic and data
• Each frontend has a BFF (Backend for Frontend) that adapts the core API to what that frontend needs

This works well when:

• web/mobile/admin have very different needs
• you want to avoid overloading the core backend with UI-specific concerns
• teams work independently

Practical answer

• Small project: usually one backend is enough
• Medium/large project: often use shared backend + BFFs
• Only split backends per frontend if the frontends are truly different enough to justify it

Decision factors

Consider separate backends if:

• each frontend has very different data requirements
• release cycles are independent
• performance/latency needs differ a lot
• security boundaries differ
• different teams own the frontends

Keep a shared backend if:

• the domain logic is mostly the same
• you want to minimize duplication
• the product is still evolving quickly

If you want, I can also sketch a simple architecture diagram for:

1. one backend for all frontends, or
2. shared backend + BFFs.