How long should a software requirements document be for an MVP?

Keep it concise. For a standard MVP, a 5 to 10-page document (or 15 to 20 detailed user stories) is usually enough to define core features clearly.

What is the difference between a PRD and a functional specification?

A PRD (Product Requirement Document) focuses on product goals, user needs, and features from a business perspective. A functional spec details the technical behavior and system architecture required to build those features.

Do non-technical founders need design mockups before writing requirements?

No. Simple visual sketches or wireframe flows are helpful, but you do not need final designs. Your specs should focus on functionality and business logic first.

How do software requirements stop scope creep?

Clear requirements establish explicit boundaries. When new feature ideas pop up mid-build, you can compare them to your out-of-scope list and defer them to future updates.

Should I use AI tools to generate my software requirements document?

AI tools can help draft user stories and outline edge cases quickly. However, you must review and refine every requirement to ensure it aligns with your specific business goals and user workflows.

All postsAugust 10, 2026

How to Write Software Requirements: A Founder Guide

Learn how to write software requirements without technical jargon. Clear specifications prevent dev delays, lower costs, and protect runway.

Building software without clear specs is like building a house without blueprints. You ask for a quick front porch. The builder constructs a giant garage with a moat. You pay double, lose three months, and still cannot sit outside.

Most non-technical founders panic when developers ask for a Software Requirements Document (SRD) or Product Requirement Document (PRD). You might think you need a computer science degree to write one. You do not.

Writing software requirements is simply explaining what your product does, who uses it, and how it behaves when things go wrong. Do this right, and you protect your startup budget and keep your dev team moving fast.

Why Software Requirements Fail

Dev builds break down when assumptions replace clear instructions. If you tell an engineer to build a simple login page, you think of an email and password field. The engineer might build a social login system, a password reset workflow, and multi-factor authentication. Suddenly, two days of work turn into two weeks.

Clear specs stop assumptions in their tracks. When you learn how to scope a software project without scope creep, clear specs become your strongest shield. They protect your timeline and keep costs predictable.

Without clear specs, developers make educated guesses. Those guesses often turn into messy code base fixes later, compounding technical debt for startups before you even launch.

The 4 Core Parts of a Software Requirements Document

You do not need fifty pages of technical jargon. You need four clean sections that explain what you want built.

1. User Stories (Who Needs What and Why)

Skip the technical language. Write user stories instead. Use this simple template: As a [user type], I want to [action] so that [benefit].

For example:

"As a store manager, I want to filter sales by date so that I can write my weekly report."
"As a customer, I want to save my credit card so that I can check out faster next time."

This gives your dev team context. Engineers solve problems better when they know why a feature exists.

2. Acceptance Criteria (The Definition of Done)

A feature is not done when code is written. It is done when it works exactly as expected. Acceptance criteria define success.

For a password reset feature, your criteria might look like this:

User enters their account email.
System sends a reset link within 30 seconds.
Link expires after 15 minutes.
Invalid emails trigger a helpful error message.

When you set clear rules, QA testers know what to verify before code goes live.

3. Visual Flow and Rough Wireframes

Developers are visual builders. Text alone leaves room for misinterpretation. You do not need polished design files. Sketched screens on paper or simple wireframes in tools like Figma work fine.

Show how screens link together. What happens when a user clicks "Submit"? What screen shows up next? Mapping this visual journey links your requirements back to your overall software product roadmap so everyone sees the big picture.

4. Out-of-Scope List (What NOT to Build)

What you skip is just as important as what you build. Explicitly list features you are not building in this version.

If you are building an MVP messaging tool, your out-of-scope list might include:

No voice notes.
No file attachments above 5MB.
No custom emojis.

Putting boundaries on your build prevents features from expanding mid-project.

3 Mistakes Non-Technical Founders Make

Writing How, Not What

Your job is to define product requirements, not the database structure. Tell developers what the system should do for the user. Let them decide how to engineer the database or select the underlying infrastructure.

Ignoring Edge Cases

What happens when a user submits a form without filling in required fields? What happens when their credit card gets declined? What if two users edit the same profile at once? Unhandled edge cases create bugs that frustrate real users globally.

Skipping the Feedback Loop

Never send a specs document over email and assume developers understand everything. Run a walkthrough session. Let your developers ask questions, challenge assumptions, and spot logical gaps.

How to Hand Off Requirements to Developers

Once your document is ready, review it with your team or agency. If you are still evaluating partners, use your requirements document when you vet a software agency. A good team will question your specs, suggest simpler alternatives, and help you cut unnecessary complexity.

If an agency accepts a vague prompt without asking questions, run. Good dev teams demand clarity because they want to ship software that actually works.

Turn Your Product Vision Into Clean Code

Writing software requirements does not have to feel overwhelming. Keep your specs simple, focus on user outcomes, and establish clear boundaries early.

Need help turning your napkin sketch into a clear software specification? At Zevas Tech, we work with founders globally to refine product strategies, scope smart MVPs, and build custom software that scales. Let's talk about your build.