Free App Requirements Generator
Generate a complete requirements specification with functional, non-functional, and constraints from your app description.
Skip the spec doc. Build the app itself with RapidNativeTry an example
How to Write Software Requirements
Start with the Problem
Great requirements begin with understanding the problem, not the solution. Interview users, observe workflows, and identify pain points before writing any specifications. Requirements should trace back to specific user needs or business goals.
Be Specific and Testable
Every requirement should be specific enough to be verified. Instead of "the app should be fast," write "API responses must complete within 500ms at the 95th percentile." If you cannot write a test case for it, the requirement is too vague.
Separate What from How
Requirements describe what the system must do, not how it will do it. Avoid prescribing specific technologies or implementations unless they are actual constraints. "Users must be able to reset passwords" is a requirement — "Use bcrypt for password hashing" is an implementation detail.
Prioritize Ruthlessly
Use MoSCoW to separate essential features from nice-to-haves. If everything is Must Have, you will miss deadlines. Force yourself to label at most 50 percent of requirements as Must Have. This discipline prevents scope creep and enables on-time delivery.
Document Out of Scope
Explicitly listing what is NOT in the requirements is as important as what is. This prevents scope creep, sets stakeholder expectations, and provides a clear roadmap for future releases. Out of scope today does not mean out of scope forever.
Types of Requirements
Every app needs both functional and non-functional requirements to succeed.
| Type | What It Defines | Example |
|---|---|---|
| Functional | What the system must do | Users can reset password via email link |
| Performance | Speed and responsiveness | API responses under 500ms at p95 |
| Security | Data protection and access control | All data encrypted at rest and in transit |
| Scalability | How the system grows | Supports 10,000 concurrent users |
| Usability | Ease of use | First-time users complete signup in under 60s |
| Reliability | Availability and fault tolerance | 99.9% uptime, graceful error handling |
| Accessibility | Inclusive design | WCAG 2.1 AA compliant |
Prioritizing with MoSCoW
Must Have (50%)
Critical for launch. The product cannot ship without these requirements and users will abandon it without them. Examples: user authentication for a social app, checkout for an e-commerce app, core data persistence.
Should Have (30%)
Important but not critical. Workarounds exist if not included, but the product would be significantly less valuable. Examples: search functionality, push notifications, profile customization, basic analytics.
Could Have (20%)
Nice-to-haves that improve user experience. First to be cut if time runs short. Examples: dark mode, social sharing, animation polish, advanced filters, export features.
Won't Have
Explicitly out of scope for this release. Documented separately to prevent scope creep. Examples: admin dashboard, third-party integrations, localization for additional languages, advanced reporting.