Non-functional requirements describe how well a system must perform, scale, and operate under real-world conditions.
What are non-functional requirements?
Non-functional requirements, often shortened to NFRs, define quality attributes and technical constraints. They do not describe features directly, but they strongly affect architecture, infrastructure, QA scope, and delivery effort.
While functional requirements explain what the system must do, NFRs define how well it must do it.
Example
A fintech product may define requirements such as:
- checkout API response under 300 ms,
- secure password hashing,
- minimum monthly availability of 99.9%.
Why non-functional requirements matter
- They shape architecture and infrastructure decisions.
- They can significantly change delivery effort and cost.
- They reduce production risk.
- They make quality expectations explicit before implementation starts.
Common NFR categories
- Performance: Page speed, API response time, processing limits.
- Scalability: Traffic spikes, concurrency, growth expectations.
- Security and compliance: Encryption, access control, regulatory obligations.
- Compatibility: Browsers, devices, operating systems, or screen sizes.
Common mistakes
- Leaving NFRs out of the estimate entirely.
- Defining them too vaguely to test.
- Adding them too late, after architecture decisions are already made.
- Treating them as optional instead of core delivery constraints.
How Apropo supports the workflow around non-functional requirements
Apropo does not expose a dedicated non-functional requirements model in the confirmed frontend, but it can support the surrounding workflow through structured scope, descriptions, and collaborative review.
- Structured hierarchy helps teams keep requirement-related scope attached to a clear project model.
- Descriptions provide a place to keep contextual detail tied to the project rather than scattered across separate notes.
- Templates help standardize recurring scope patterns that often depend on quality or operational constraints.
- Shareable proposal views make the current requirement interpretation easier to review with stakeholders.
How Apropo helps refine NFR-related scope
That makes Apropo useful for reviewing and operationalizing NFR-adjacent scope even though a dedicated NFR entity was not confirmed in the product scan.
- Comments help capture clarification around quality expectations, operational limits, or technical constraints.
- Version history helps teams revise the scope after those discussions without losing the prior state.
- Jira export helps carry the reviewed structure into delivery planning.
- Templates and reusable library elements help teams keep recurring structure more consistent across projects.