What non-functional requirements (NFR) do you specify in projects?

Non-functional requirements (NFR) describe qualities of a system that are not directly related to its functionality but affect usability, performance, and reliability.

Main types of NFRs often described in projects:

• Performance: response time, throughput, load.
• Reliability: fault tolerance, mean time between failures.
• Scalability: the system's ability to grow and handle increasing data or user volume.
• Security: authentication, authorization, data protection.
• Usability: interface convenience, accessibility.
• Maintainability: ease of making changes and fixes.
• Compatibility: operation across different platforms, browsers, devices.
• Availability: the time when the system is accessible to users.
• Localization: support for different languages and regional settings.

Example: for a web application, it can be specified that the API response time should not exceed 200 ms under a load of up to 1000 concurrent users, and the system should ensure 99.9% uptime.