What project in your career was the most challenging and why?

The most challenging project in my career was a large corporate portal with high load and complex business logic. The main difficulties were:

• Integration with many external services and APIs, which often changed.
• Ensuring scalability and fault tolerance as the number of users grew.
• Optimizing performance when working with large volumes of data.
• Coordinating the work of a team of several developers and maintaining code quality.

To solve these problems, it was necessary to implement a modular architecture, use caching, carefully design the database, and automate testing and deployment.