What is a Backend for Frontend?

A Backend for Frontend (BFF) is a backend service built specifically to serve one particular frontend application or client type, such as:

• a web app
• a mobile app
• a desktop app
• a smart TV app

Instead of having the frontend talk directly to many backend services, the BFF acts as a tailored middle layer that:

• aggregates data from multiple services
• formats responses the way that frontend needs
• hides backend complexity
• reduces network calls
• handles client-specific logic

Why use a BFF?

Different frontends often need data in different shapes or have different performance needs. For example:

• a mobile app may need fewer fields and smaller payloads
• a web app may need more detailed data
• a TV app may need a simpler navigation-focused response

A BFF lets each frontend have an API designed for its exact needs without forcing all clients to use the same generic backend API.

Example

Suppose a page needs:

• user profile data
• recent orders
• recommendations

Without a BFF, the frontend might call three separate services.
With a BFF, the frontend calls one BFF endpoint, and the BFF gathers and combines the data into a single response.

Benefits

• simpler frontend code
• fewer round trips
• APIs tailored to each client
• better security/control over backend access
• easier to evolve frontend independently

Tradeoffs

• more services to maintain
• possible duplication of logic across BFFs for different clients
• additional backend layer to operate

In short

A BFF is a backend tailored to one specific frontend, designed to make that frontend simpler, faster, and easier to support.