Why Non-Functional Requirements Matter: A Guide for Product Managers

While features and functions grab the spotlight, non-functional requirements (NFRs) quietly govern the success of your product. These requirements define how well your system operates, not just what it does.

Non-functional requirements, often abbreviated as NFRs, are the qualities that make a product usable, performant, reliable, secure, maintainable, and scalable. They're often overlooked, but they're essential for building products that users love and that businesses can rely on.

Some types of Non-Functional Requirements

NFRs can be classified into a variety of categories, but some of the most common include:

• Usability: How easy is the product to learn and use? Can users complete their tasks quickly and efficiently?
• Performance: How fast is the product? How quickly does it respond to user input? Can it handle a large number of users and requests simultaneously?
• Reliability: How often does the product crash or experience errors? How much downtime can the product afford?
• Security: How well will the product protect user data from unauthorized access and modification?
• Scalability: How easily can the product be scaled to meet the needs of a growing user base?
• Maintainability: How easy is the product to update and fix bugs in?
• Compliance: Does the product adherence to laws, regulations, standards, and company policies?

Big tech companies are heavily invested in NFRs

Spotify pushes the boundaries of network optimization by partnering with internet service providers and peering directly with major internet exchanges. This eliminates bottlenecks and latency, resulting in a near-instantaneous music streaming experience.

Cover from 'The Playlist' (2022)

Utilizing a global network of content delivery servers and employing techniques like content pre-fetching and intelligent caching, Spotify aims to deliver music within milliseconds, regardless of a user's location.

The delay is 500 milliseconds but it's still too slow for Daniel. Andreas Ehn will have to innovate with a brand new network protocol.

Amazon focuses on scalability and reliability. Amazon's website is able to handle large volumes of traffic during peak shopping periods, such as Black Friday and Cyber Monday. Amazon is able to achieve this by investing heavily in its infrastructure and using a variety of techniques to distribute traffic across its servers.

Netflix invests a lot of effort in perfecting its high quality video streaming experience. They rely heavily in its content delivery network and the use of a variety of techniques to optimize the streaming experience. For example, Netflix uses a technique called adaptive bitrate streaming to adjust the quality of the video stream based on the user's internet connection speed.

Google stands for excellence in speed, accuracy and relevance. Google engineers spend a lot of time thinking about how to improve the performance and usability of Google Search. They implemented a variety of caching techniques to improve speed and a variety of machine learning algorithms to deliver accurate results.

Apple is well know for designing from the ground up with security in mind. Features like end-to-end encryption, multi-factor authentication, and rigorous hardware security audits create a robust defense against cyberattacks. They minimize data collection, limit third-party access, and provide transparent user controls over their information. This commitment to user privacy sets them apart in an era of increasing online surveillance.

Key takeaways

• Non-functional requirements (NFRs) are essential for building products that users love and that businesses can rely on. NFRs include qualities such as usability, performance, reliability, security, scalability, compliance, and maintainability.
• Successful companies like Spotify, Amazon, Netflix, Google and Apple have all considered NFRs as key for their businesses.