What a Good Software Requirements Document Actually Looks Like

The Structure

A good requirements document has five sections:

1. Context & Goals (1 page)
2. User Roles & Workflows (2-3 pages)
3. Functional Requirements (5-8 pages)
4. Non-Functional Requirements (1-2 pages)
5. Constraints & Assumptions (1 page)

Total length: 10-15 pages. If your requirements document is 30+ pages, you've lost clarity. If it's 3 pages, you've hidden critical information.

Section 1: Context & Goals

Start with the problem you're solving. Not the solution. The problem.

Bad version: "We need a new software system to manage our sales pipeline."

Good version: "Our sales team currently tracks deals in three places: Salesforce, a shared spreadsheet, and email. This causes data inconsistency (deals are stale in Salesforce by 30 days), prevents visibility (managers can't see active deals for individual reps), and wastes 6 hours per week on data reconciliation. Our goal is to create a single source of truth for active deals where data is current within 24 hours, managers can see pipeline health by rep, and data entry happens once."

Notice the difference. The good version tells you:

• The current state and why it's broken
• The desired state with specific metrics (24 hours, one data entry point)
• The business impact (6 hours per week waste)

Follow this with 3-5 specific goals. Not "improve efficiency"—that's worthless. Instead:

• "Reduce time spent on deal data entry from 90 minutes per week per rep to <15 minutes per week"
• "Ensure deal data is accurate within 24 hours of status change"
• "Enable pipeline visibility: managers can see all deals for their team with one click, drill down to any individual deal's history"

Each goal should answer: what success looks like, measured how, and why you care.

Section 2: User Roles & Workflows

Who uses this system? Not "salespeople." Which salespeople? Reps with $0-5M in deals? Partners with $50M+ in deals? VPs managing reps?

For each role, describe:

• Role name: Sales Rep (New)
• Daily volume: Manages 15-30 active deals
• Key workflow: Creates deal in CRM within 1 day of discovery, updates deal status twice a week based on client interactions, queries pipeline to prepare for weekly forecast call
• Success criteria: Can create a deal in <2 minutes, can update deal status from mobile when in a client meeting, can run a pipeline report by source in <1 minute
• Constraints: Uses CRM 60% of the workday, often in client meetings with no desktop access, has varying technical comfort levels

Now describe their workflow step-by-step. Not a general description. An actual workflow:

"Sales Rep Reviews Daily Pipeline"

1. Rep opens system at 9 AM
2. System shows deals that changed in last 24 hours, highlighted
3. Rep can filter by: deal source, deal size, deal stage, rep
4. Rep sees each deal's history: when created, last updated, current stage, next milestone date
5. Rep can update stage with one click and add a note
6. Rep can tag a deal for attention in morning forecast call

This is testable. A developer reads this and knows exactly what "reviewing pipeline" means.

Every workflow for every role gets this treatment. It's tedious to write. It's invaluable when the developer's building.

Section 3: Functional Requirements

Functional requirements describe what the system does. This is where most documents fail—they're too vague or too granular.

Too vague: "The system shall allow users to create deals and track their progress."

Too granular: "The system shall provide a text input field with a maximum length of 255 characters for deal name. The field shall appear on the left side of the screen. The font shall be 14pt. When the user clicks the Save button, the system shall validate that the field is not empty and display an error message if it is."

Just right: "Users can create a deal by entering: deal name (required, 255 character max), company name (required), deal size in dollars (required), expected close date (required), deal source (required, dropdown with predefined sources), and optional notes. After creation, the system displays the deal with all fields editable except deal source. The system shows a unique deal ID and creation timestamp."

Notice what this includes:

• The data model (which fields exist)
• Which fields are required
• Data types and constraints (max length, dropdown)
• Behavior after creation (what the user sees)

For each major feature, write 4-8 requirements like this. Be specific about:

• Data: What information is stored, how much can it be, what's required
• Behavior: What happens when the user takes an action
• Feedback: What does the user see after they act
• Rules: When does validation fail, what happens then

Example requirements for deal management:

"Deals display in a pipeline view showing columns for each deal stage: Prospect, Qualified, Proposal, Negotiation, Won, Lost. A deal appears in one stage at a time. Deals can be moved between stages by dragging. When a deal is moved, the system records the stage change timestamp and asks the user to add a note (optional). The user can click a deal to open full details in a sidebar."

"A deal cannot be moved from Proposal or Negotiation back to Prospect. A deal in Won stage cannot be moved. Only the deal owner or a manager can move a deal. The system shows who moved a deal and when in the deal's history."

This is concrete enough that a developer can build it. It's specific enough that you know what you're getting.

Section 4: Non-Functional Requirements

Non-functional requirements describe how the system works, not what it does.

Performance:

• Page loads take <2 seconds for views with <500 deals
• Searches across 5,000 deals complete in <1 second
• Mobile app works on 4G connections (tested at 3 Mbps)

Security:

• All data transmits over HTTPS
• User passwords are salted and hashed
• API access requires authentication token (expires after 30 days of inactivity)
• Only deal owner or manager can view deal details

Reliability:

• System is available 99.5% of the time (30 minutes downtime per month allowed)
• Automated daily backups, tested monthly for restoration
• If database connection fails, user sees "Connection lost" message and can try again

Usability:

• First-time user can create their first deal without training in <5 minutes
• Mobile app works with one hand (for thumb navigation)
• System works in Chrome, Safari, Firefox (latest versions)

These aren't nice-to-haves. They're requirements that prevent expensive surprises. A system built for 500 concurrent users will fail if you suddenly need 5,000. A mobile app that requires both hands is unusable in certain contexts.

Section 5: Constraints & Assumptions

Spell out what's NOT included and why. And what you're assuming to be true.

Constraints:

• We will not integrate with legacy ERP system (too expensive)
• We will not support data migration from legacy CRM (users will manually re-enter deals)
• We will not build a native mobile app initially (will use responsive web)
• We will not support multiple currencies in phase 1

Assumptions:

• We assume users have internet access during work hours
• We assume reps won't manage >200 active deals at once
• We assume data is accurate when entered (we won't implement data validation against external sources)
• We assume users have basic comfort with web applications

These prevent scope creep. When someone asks "can we integrate the legacy system?" you point to the constraints section and explain why that decision was made.

Examples That Work

Here's a complete requirement for context:

Feature: Deal Pipeline Dashboard

"The dashboard displays all deals a user owns in a Kanban-style pipeline view with five stages: Prospect, Qualified, Proposal, Negotiation, Won. The dashboard loads all deals owned by the user in real time. When another user (or the same user in another window) moves a deal, the first user's view updates within 5 seconds. Users can filter by deal source (required, preset list) and company (optional text search). Deals appear as cards showing: deal name (truncated if >30 characters), company name, deal size, and next milestone due date. Users can drag and drop deals between stages. When a deal moves, the system records the timestamp and the user ID of who moved it. Users can click a deal to open the full deal record in a sidebar. The dashboard works on desktop and mobile (in mobile view, stages appear in a scrollable horizontal list instead of side-by-side)."

This requirement tells you:

• What data displays
• How data updates (real-time, 5-second sync)
• How users interact (filter, drag-drop, click)
• What the system records (movement history)
• How it varies by device

A developer can build this. You can test it. There's no ambiguity.

How to Write One

Start simple. Choose one core workflow (for the sales rep example: create and update deals). Write that workflow in step-by-step detail. Then define every piece of data that appears in that workflow.

For each data piece, define:

• What it is
• What format it's in
• Whether it's required
• What happens when it's edited
• Who can edit it

Next, add one more workflow. Then one more. You're building a complete picture of how the system works, piece by piece.

Have your team—especially the people who will use the software—review it. Ask: "Is this how you actually work?" If they say "not quite, we also need to..." you've found missing requirements.

Get sign-off. Once your team agrees this is what you want built, lock it. Changes are expensive once building starts.

Related Reading

Understanding requirements is critical whether you're building vs. buying or planning for the real cost of development.

What Makes a Requirements Document Fail

• Vagueness: "The system should be fast" is not a requirement. "<2 second page load" is.
• Missing workflows: You describe features in isolation without showing how they connect
• Technology jumping: "We'll use React and Node.js" has no place here. Focus on what the system does, not how it's built
• Missing edge cases: What if a user creates a deal and then immediately deletes it? What if two users try to move the same deal simultaneously?
• Incomplete user roles: You describe a sales rep's workflow but forget that managers need different views and permissions

The best requirements documents come from people who've actually done the work. If you're building sales software, talk to sales people. Sit with them. Watch them work. Then document what you see.

The document isn't the truth. The actual work is the truth. The document is just your best attempt to capture it before building starts.

Get that right, and building goes smoothly. Get it wrong, and you'll spend months in rework.

Need Help Writing Requirements?

A good requirements document is the foundation of a successful software project. If you're building custom software and want to make sure your requirements are solid, book a discovery call with us. We'll help you think through the critical pieces and catch potential issues before they become expensive problems.