05/12/2023 0
NFR Requirements: The Ultimate Checklist for Non-Functional Requirements

NFR Requirements specify criteria used to judge the operation of a system, rather than specific behaviors. They contrast with functional requirements that define specific functions or behaviors.

NFRs can include scalability, availability, maintenance, and portability. They are important for guiding the design and functionality of a software system. NFRs are typically categorized as non-functional requirements or quality attributes. These requirements describe the system's operational capabilities and constraints, aiming to improve its functionality.

They encompass aspects such as speed, security, reliability, and data integrity. In an agile development approach, NFRs serve as constraints and guide the design of the solution. Overall, NFRs play a crucial role in ensuring the quality and effectiveness of a software system.

What Are Non-functional Requirements?

Definition Of Non-functional Requirements

Non-functional requirements, also known as NFRs, are a category of requirements in systems engineering and requirements engineering that specify criteria for evaluating the operation of a system rather than its specific behaviors or functions. These requirements help to define the qualities and attributes of a system, ensuring that it meets the desired performance, usability, security, and reliability standards.

Difference Between Non-functional And Functional Requirements

While non-functional requirements focus on the overall qualities and attributes of a system, functional requirements define specific behaviors and functions that the system should exhibit. Functional requirements outline how the system fulfills the desired tasks and activities, while non-functional requirements ensure that the system performs optimally in terms of factors such as scalability, availability, and maintainability.

Importance Of Non-functional Requirements In System Design

Non-functional requirements play a crucial role in system design as they help shape the overall performance and user experience. By considering non-functional requirements from the early stages of development, system designers can make informed decisions that will result in a robust and efficient system. These requirements also serve as a guide for prioritizing system attributes and determining trade-offs when conflicts arise. In addition, non-functional requirements contribute to the overall quality of the system, ensuring that it is usable, reliable, secure, and easy to maintain. They help prevent issues such as performance bottlenecks, data breaches, and compatibility problems, which can have a significant impact on user satisfaction and the system's success in the long run. By understanding the importance of non-functional requirements and incorporating them into the system design process, organizations can deliver high-quality systems that meet user expectations and achieve their business goals. NFR TV SCHEDULE

Types Of Non-functional Requirements

Non-functional requirements play a crucial role in determining the overall performance and quality of a system. They define the criteria that can be used to judge the operation of a system, focusing on aspects other than specific behaviors or functions. In this section, we will explore several types of non-functional requirements that are essential to consider during the development process.


Scalability refers to the system's ability to handle an increasing workload without sacrificing performance. It ensures that the system can smoothly scale up or down based on the changing demands. An application's scalability is critical in meeting the growing needs of users and accommodating increasing usage without causing performance issues.


Availability is a crucial non-functional requirement that ensures the system is accessible and usable whenever it is needed. It involves minimizing downtime, maximizing uptime, and implementing strategies to handle failures effectively. A highly available system provides uninterrupted service to its users, ensuring their needs are met without disruptions.


Maintainability focuses on the ease with which a system can be maintained, updated, and modified over time. It involves using well-structured and modular coding practices, providing clear documentation, and adopting standardized development processes. A maintainable system allows developers to make changes efficiently, reducing the cost and effort required for future enhancements.


Portability refers to the ability of a system to run on different platforms or environments with minimal modifications. It ensures that the application can be easily deployed and used across various hardware and software configurations. Having a portable system enables flexibility, allowing it to reach a broader user base without significant adaptability challenges.


Performance is a crucial non-functional requirement that measures how well a system performs under specific conditions. It includes factors such as response time, throughput, and resource utilization. A high-performance system delivers efficient and fast responses, ensuring a smooth user experience and meeting the performance expectations of stakeholders.


Usability focuses on the user experience and the ease with which users can interact with the system. It involves designing intuitive interfaces, providing clear instructions, and minimizing the learning curve. A usable system is intuitive, efficient, and user-friendly, allowing users to achieve their goals quickly and effectively.


Security is an essential non-functional requirement that aims to protect the system from unauthorized access, data breaches, and other malicious activities. It involves implementing proper authentication, encryption, and access control mechanisms. A secure system ensures the confidentiality, integrity, and availability of sensitive information, preventing potential security risks.


Reliability focuses on the system's ability to perform consistently and predictably under different conditions. It involves minimizing failures, recovering from errors gracefully, and ensuring data integrity. A reliable system provides consistent outputs and minimizes disruptions, inspiring trust and confidence among users.


Robustness refers to the system's ability to handle unexpected situations or errors without crashing or causing significant disruptions. It involves implementing proper error handling mechanisms, performing thorough testing, and incorporating redundancy where necessary. A robust system can gracefully handle errors and recover from failure, maintaining its functionality and integrity. In conclusion, understanding and addressing various types of non-functional requirements are essential for developing high-quality, performant, and reliable systems. By considering scalability, availability, maintainability, portability, performance, usability, security, reliability, and robustness, developers can create systems that meet the expectations and needs of users while ensuring long-term success and sustainability.

Examples Of Non-functional Requirements

Non-functional requirements are criteria that can be used to judge the operation of a system. They define the qualities and characteristics that the system must possess in order to fulfill its purpose effectively. These requirements are essential for creating a high-performing and user-friendly system. Here are some examples of non-functional requirements:

Scalability: The System Must Be Able To Handle A Large Number Of Concurrent Users Without Any Degradation In Performance.

Scalability is crucial for systems that receive heavy traffic or experience rapid growth. The ability to handle a large number of users without compromising performance ensures smooth and uninterrupted user experience. Whether it's a website, an online platform, or a mobile application, scalability is vital to accommodate increasing user demands. By implementing efficient load balancing and resource allocation, the system can effectively handle a surge in user traffic without any negative impact on its performance.

Availability: The System Must Be Available 24/7 With Minimal Downtime For Maintenance Or Updates.

Availability is a critical requirement for systems that need to be constantly accessible to users. Whether it's an e-commerce website, a communication platform, or a banking application, users expect the system to be available at all times. In cases where downtime is necessary for maintenance or updates, it should be kept to a minimum, preferably during off-peak hours. By ensuring high availability, the system can meet user expectations and avoid potential revenue losses or customer dissatisfaction.

Maintainability: The System Must Be Easily Debugged And Updated Without Impacting Its Functionality.

Maintainability is essential to keep the system in good working condition and adapt it to changing requirements. With regular updates and bug fixes, the system can provide an optimal user experience and remain compatible with evolving technologies. An easily maintainable system allows developers to identify and fix issues promptly, ensuring smooth operation and reducing overall downtime. Employing clear code structure, thorough documentation, and automated testing can significantly enhance the system's maintainability.

Portability: The System Should Be Able To Run On Different Operating Systems Without Requiring Significant Changes.

Portability is crucial for systems that need to be compatible with various operating systems. Whether it's a desktop application, a mobile app, or a web-based platform, the ability to run seamlessly on different operating systems enhances the system's reach and usability. By minimizing system dependencies and utilizing cross-platform frameworks, developers can create a portable system that can be easily deployed across multiple platforms with minimal code changes.

Performance: The System Must Respond Quickly To User Requests And Handle A Large Volume Of Data Efficiently.

Performance is a vital requirement for systems that deal with large amounts of data or have critical response time requirements. Whether it's a search engine, a real-time analytics platform, or a financial transaction system, users expect quick and accurate responses to their requests. The system should be optimized to process and retrieve data efficiently, ensuring minimal latency and high responsiveness. Employing caching mechanisms, efficient algorithms, and hardware optimizations can significantly improve the system's performance.

Usability: The System Must Have An Intuitive And User-friendly Interface.

Usability is crucial for systems that aim to provide a positive user experience. Whether it's a mobile application, a website, or a software tool, users should be able to navigate and interact with the system effortlessly. An intuitive interface, clear navigation, and well-designed user interactions contribute to a user-friendly system. By conducting user research, usability testing, and incorporating user feedback, developers can create a system that meets user expectations and minimizes user frustration.

Security: The System Must Have Robust Security Measures In Place To Protect Against Unauthorized Access And Data Breaches.

Security is of utmost importance for systems that handle sensitive data, facilitate transactions, or require user authentication. Ensuring the confidentiality, integrity, and availability of data is crucial for maintaining user trust and complying with data protection regulations. The system should implement robust authentication mechanisms, data encryption, access control, and threat detection systems to safeguard against unauthorized access and data breaches.

Reliability: The System Must Consistently Perform According To Its Specifications Without Unexpected Failures.

Reliability is a fundamental requirement for systems that need to perform consistently and predictably. Whether it's an industrial control system, a voting application, or an autonomous vehicle software, the system should adhere to its specifications and minimize unforeseen failures. Implementing rigorous testing, robust error handling mechanisms, and redundancy measures can significantly enhance the system's reliability and mitigate the risk of critical failures.

Robustness: The System Must Gracefully Handle Errors And Exceptions Without Crashing Or Losing Data.

Robustness is important for systems that encounter errors or exceptional circumstances. Instead of crashing or losing data, the system should handle errors gracefully and recover without user intervention. Robust error handling, data validation, fault tolerance, and backup mechanisms ensure that the system remains operational and data integrity is maintained even in the face of unexpected situations.

Approaches To Eliciting Non-functional Requirements

When it comes to gathering non-functional requirements for a project, there are several approaches that can be used to ensure a comprehensive understanding of the desired system attributes. By employing a combination of these techniques, stakeholders can provide valuable input that will shape the development process. Below are some effective approaches for eliciting non-functional requirements:

Interviews With Stakeholders

Conducting interviews with stakeholders is a crucial step in eliciting non-functional requirements. By engaging in direct conversations, project teams can gain valuable insights into the expectations, preferences, and constraints of the stakeholders. These interviews can be one-on-one or conducted in a group setting, tailored to the specific needs of the project.

Surveys And Questionnaires

Surveys and questionnaires are useful when a large number of stakeholders are involved or when reaching out to a geographically dispersed audience. These methods allow for a structured approach to gathering non-functional requirements, as stakeholders can provide their input at their convenience. Surveys can include both open-ended questions and multiple-choice options to ensure a comprehensive understanding of the desired system attributes.

Collaborative Workshops

Collaborative workshops bring stakeholders and project teams together in a focused setting. This approach encourages active participation and collaboration among participants, fostering creativity and innovation. Through facilitated discussions, brainstorming sessions, and group activities, workshops provide a valuable opportunity to gather non-functional requirements collectively and in real-time.

Prototyping And User Testing

Prototyping and user testing involve creating prototypes or mock-ups of the system to gather feedback from stakeholders. By allowing stakeholders to interact with a visual representation of the system, project teams can gather valuable insights into the desired user experience and identify any potential non-functional requirements that may arise during usage. This approach provides a tangible and practical way to validate and refine non-functional requirements.

Analysis Of Existing Systems

Analyzing existing systems that serve a similar purpose or have similar attributes can provide valuable insights into non-functional requirements. By studying the strengths and weaknesses of existing systems, project teams can identify areas for improvement and gather non-functional requirements that align with the desired system attributes. This approach allows for informed decision-making based on real-world examples.

In conclusion, the approaches to eliciting non-functional requirements outlined above provide project teams with a range of techniques to gather valuable input from stakeholders. By utilizing a combination of interviews, surveys, workshops, prototyping, and analysis of existing systems, project teams can ensure a comprehensive understanding of the non-functional requirements, leading to the successful development of a system that meets the desired attributes and expectations.

Implementing Non-functional Requirements In Agile Development

When it comes to developing software using the agile methodology, it is essential to consider not only the functional requirements of the system but also the non-functional requirements (NFRs) that define the criteria for judging the system's operation. Integrating NFRs into the agile development process ensures that the end product meets the highest standards of performance, scalability, availability, and maintainability.

Integration Of Non-functional Requirements In User Stories And Epics

One way to implement NFRs in an agile development environment is by integrating them into user stories and epics. By including non-functional requirements alongside functional requirements in the user stories, teams can ensure that NFRs are prioritized and addressed throughout the development process. For example, a user story for an e-commerce application may include both functional requirements related to cart checkout and non-functional requirements related to system scalability and availability.

Continuous Testing And Monitoring

Continuous testing and monitoring are crucial for ensuring that the software meets the defined non-functional requirements. In an agile development setup, this means incorporating automated and continuous testing processes into the development pipeline. By running tests regularly throughout the development lifecycle, teams can identify and address any performance or availability issues early on.

Moreover, continuous monitoring allows teams to keep track of the system's performance in real-time. This enables them to detect any deviations from the desired non-functional requirements and take necessary actions to optimize the system's performance further.

Iterative Improvements Based On User Feedback

Agile development methodologies focus on delivering value to the end-users. Therefore, it is essential to continuously gather and incorporate user feedback to improve the system's non-functional aspects. By utilizing feedback loops, teams can identify areas where the system may be falling short of meeting NFRs and make the necessary iterative improvements to enhance the overall user experience.

Balancing Non-functional Requirements With Agile Principles

In agile development, it is crucial to strike a balance between non-functional requirements and the core principles of agility, such as flexibility, adaptability, and quick delivery of value. While NFRs are essential for ensuring the system's performance and quality, they should not hinder the agility of the development process.

To achieve this balance, teams need to identify the critical non-functional requirements early on and make strategic decisions on how to approach them. This may involve breaking down large NFRs into smaller, manageable pieces, prioritizing them based on business and user needs, and aligning them with the overall project goals.

Frequently Asked Questions Of NFR Requirements

What Are The 4 Types Of Non-functional Requirements?

The 4 types of non-functional requirements are scalability, availability, maintenance, and portability. Scalability refers to the system's ability to scale up or down as needed. Availability means the system must be available when needed. Maintenance focuses on the system being easy to maintain and update.

Finally, portability refers to the system's ability to run on different platforms with minimal changes.

What Is NFR System Requirements?

In systems engineering and requirements engineering, non-functional requirements (NFRs) are criteria used to judge the operation of a system, rather than specific behaviors. They specify the properties of a software system that sit outside of specific features and functionality. NFRs include scalability, availability, maintenance, and portability.

NFRs are system qualities and often serve as constraints in the design and development process.

What Type Of Requirement Is NFR In Agile?

Non-functional requirements (NFRs) in agile refer to the criteria that judge the operation of a system, rather than its specific behaviors. They guide the design of the solution and serve as constraints across relevant backlogs. NFRs include qualities like scalability, availability, maintenance, and portability.

What Are The Non-functional Requirements Of Utility?

Non-functional requirements of utility include scalability, availability, maintenance, portability, and usability. These requirements focus on the operation and performance of the system, rather than specific behaviors. Non-functional requirements are essential for ensuring the system meets quality standards and performs effectively.


To ensure the success of your software system, it is crucial to pay attention to non-functional requirements (NFRs). Unlike functional requirements that define specific behaviors, NFRs focus on judging the system's operation. These criteria include scalability, availability, maintenance, portability, and more.

NFRs guide the design of your solution and serve as constraints in Agile development. By addressing these requirements, you can enhance the system's functionality and improve qualities such as speed, security, reliability, and data integrity. Don't overlook the importance of NFRs in creating a successful software system.