Why Contract-First Development (CFD)?

Why Contract-First Development (CFD)? Defining contracts before coding helps us gain a transparent view of the communication between systems.

Key benefits of contract-first development:

• Development teams between the systems can work in parallel because they know the interfaces (this means avoiding blockages)
• QA Automation Engineers can already start preparing automated tests based on the contracts (this fits in well with TDD)
• It helps us to get cleaner designs

A concrete example of Contract-First Development for APIs (API-First Design) – why design the REST API interface before coding it:

• It enables REST API design to be done collaboratively by both backend and frontend developers
• QA Automation Engineer is able to start writing automated tests for the REST API
• Backend developers can implement the REST API whilst frontend developers can be simultaneously implementing based on a mock version of the REST API since the interfaces are known