Extensibility-first design is a software development approach that prioritizes the ability for a digital product to be easily customized and extended over other design considerations. This means that when designing and building software, the focus is on creating a strong, flexible foundation that can be easily modified and expanded upon as needed.

One key aspect of extensibility-first design is creating modular, reusable components that can be easily integrated into different parts of the software. This allows for flexibility in how the software is used and can make it easier to add new features and functionality.

Another important consideration in extensibility-first design is building in hooks and APIs (Application Programming Interfaces) that allow for external developers to easily integrate with and customize the software. This can be particularly useful for software-as-a-service (SaaS) products, where customers may have unique requirements and needs that can be met through custom integrations.

Overall, extensibility-first design is focused on creating software that is flexible, adaptable, and able to meet the evolving needs of users. This approach can help software companies to more easily respond to changing market conditions and customer demands, leading to increased competitiveness and long-term success.