What is a Backend for Frontend?

A Backend for Frontend (BFF) is a backend service built specifically for a particular frontend application or device type.

In simple terms

Instead of having one generic backend used directly by all clients, you create a tailored backend layer for:

• a web app
• a mobile app
• a desktop app
• or even a specific frontend team/product

That BFF sits between the frontend and the core backend services.

What it does

A BFF typically:

• aggregates data from multiple backend services
• formats responses to match what the frontend needs
• reduces round trips between frontend and backend
• handles frontend-specific logic, like view composition or API translation
• hides complexity of internal services from the UI

Why use it?

Different frontends often need data in different shapes:

• Mobile might need less data and fewer calls because of bandwidth/performance constraints
• Web might need richer, more detailed responses
• Each UI may need different combinations of fields

A BFF helps each frontend get exactly what it needs without forcing the frontend to make many calls or deal with backend complexity.

Example

Imagine a dashboard page needs:

• user profile
• recent orders
• notifications

Without a BFF, the frontend might call 3 separate APIs.

With a BFF:

• the frontend calls one BFF endpoint
• the BFF calls the required services
• the BFF returns one combined response optimized for that page

Benefits

• Simpler frontend code
• Better performance
• Cleaner separation of concerns
• Easier to evolve frontend-specific needs independently

Trade-offs

• More backend services to maintain
• Possible duplication of logic across multiple BFFs
• Additional deployment and monitoring complexity

If you want, I can also show:

1. a diagram of BFF architecture, or
2. how BFF compares to an API Gateway.