How to Write a Software Requirements Specification (SRS) Document

There are plenty of horror stories about outsourced software teams and clients clashing over project requirements, and one of the most common causes is ambiguous language. Vague terms like "urgent," "pending," or "ASAP" can mean one thing to the client and something else entirely to the contractor. The parties also often carry a different picture of which features matter most.

It is rarely anyone's fault. They are simply speaking different languages. The customer has an idea for the product, its functions, and what the interface might look like. The developers are thinking about the work behind the scenes: how to write scalable, readable code, how to ensure security, how to keep the solution performant, and how to minimize bugs.

When those two viewpoints drift apart, the result is extra work, wasted budget, stress, and a weaker final product. A software requirements specification keeps them aligned from the very first day. Here in Brocoders we write one for every project we build, which is exactly why this guide uses real examples from our own SaaS product development work rather than generic templates.

TL;DR: A software requirements specification (SRS) is the document that turns a product idea into something a team can actually build, describing both functional requirements (what the system does) and non-functional requirements (how well it does it). A clear SRS based on a recognized standard such as IEEE 830 or ISO/IEC/IEEE 29148 removes ambiguity, aligns stakeholders, and is the first real deliverable of custom software development. Below is the full structure, with working examples and a template you can reuse.

What Is a Software Requirements Specification?

A software requirements specification (SRS) is a document that describes a software system to be developed. It is accessible to every party involved, including stakeholders, investors, the project manager, programmers, designers, and testers. An SRS contains three types of requirements:

1. Top-tier: the high-level business requirements. They outline the business' measurable goals, define the purpose behind the project, and align project goals with stakeholder goals.
2. Middle-tier: the user requirements. They reflect specific user needs and expectations, describe who uses the software, and highlight user interactions.
3. Bottom-tier: the product's functionality in technical terms. They identify functions, features, use cases, and non-functional requirements, describing the project as functional modules plus non-functional attributes.

By combining specifications from all three tiers, you give everyone a clear understanding of the project and measurable deliverables. This matters even more when you outsource. A thorough SRS lets a development partner communicate your requirements accurately to their own team, which is the foundation of any reliable product development process.

Here is how an SRS improves collaboration across roles:

In short, an SRS gives stakeholders, project managers, and engineers a single source of information and expectations. By compiling everything in one place, you greatly reduce the frequency of misunderstandings.

Basic Elements of an SRS

For an SRS to be useful to everyone involved, it needs several basic elements:

• Business Drivers: the reasons the customer wants the software built. This rationale guides the decisions that business analysts, system architects, and developers will make.
• Business Model: the customer business model the system must support, including organizational context, key business functions, current and future state diagrams, and process flows.
• Business and System Use Cases: typically a UML use case diagram showing the main external objects the system interacts with.
• Technical Requirements: the non-functional requirements that make up the technical environment.
• System Qualities: the non-functional requirements that determine the system's quality.
• Constraints and Assumptions: software constraints the customer requires, used to exclude options from development consideration.
• Acceptance Criteria: how the customer signs off on the final system.

Functional vs. Non-Functional Requirements: Definitions and Examples

If you are ordering custom software, you and your development team need to hash out its requirements. Skip that, and you risk a final product that is unreliable, slow, and insecure.

In software development there are two types of requirements, functional and non-functional. Within the SRS you address both.

• Functional requirements: the functions a software must perform.
• Non-functional requirements: the standards used to judge the system's operating quality.

Functional requirements help engineers capture the intended behavior of the application, expressed as services, tasks, or functions the system must perform. A non-functional requirement ensures the whole system stays usable and effective. When every functional requirement is met but the non-functional ones are weak, the system still fails to meet user needs.

Examples of functional requirements include:

• If/then behaviors
• A description of the system's workflow
• Data inputs and their corresponding outputs
• The logic behind data handling

Non-functional requirements might look like:

• Performance and scalability
• Compatibility and portability
• Maintainability, availability, and reliability
• Security
• Usability
• Localization

What Are Functional Requirements?

Functional requirements specify which functions your system (or system component) must have. In other words, they define what your custom software needs to do. When these requirements go unmet, the software fails. They are non-negotiable.

The most common functional requirement examples are use cases and document descriptions.

Use Case

Use cases can be numbered lists with text, or diagrams that describe user actions. Each use case illustrates behavioral scenarios through one or more functional requirements. First a set of use cases is selected, and then an analyst derives the functional requirements needed to fulfill each one.

The diagram below shows a navigational use-case model for a conference management system, where each main function maps to user roles:

And here is a use case numbered list for a subway ticket machine:

Written Document Descriptions

A typical written functional requirement contains a unique name and number, a brief summary, and a rationale. This helps the reader understand why the requirement is necessary and makes it easy to track. Examples of written functional requirements include:

• Interface requirements
• Data manipulation and processing requirements
• Verification requirements
• Documentation requirements
• Security requirements
• Acceptance criteria

During development, functional requirements describe whether the system works as intended. You may end up writing many requirement types before you have a complete picture of a correctly working system.

Who Is Responsible for Preparing Functional Requirements?

Functional requirements are usually a collaboration between a business analyst, system analysts, and an implementation team. The project manager makes sure they are delivered on time and signed off by the system owner and QA.

What Are Non-Functional Requirements (NFRs)?

Non-functional requirements define how the software fulfills its functional goals. They describe how the system behaves rather than what it does, setting the criteria used to evaluate performance, reliability, and maintainability. They also impose external constraints on the software and on the development process itself.

Non-functional requirements describe a specific aspect or a general property of the system as a whole, rather than an exact function.

• Aspect: a feature linked to many parts of the system but not tied to its primary function.
• Properties: characteristics of the software, including integrity, reliability, and accuracy.

Non-functional requirements split into two main categories, performance and evolutionary qualities:

Performance qualities are observed at runtime, while evolutionary qualities live in the system's static structure. Below are several non-functional requirement examples, grouped the way a classic IEEE paper presents them.

Performance

• Efficiency: how well it uses resources.
• Integrity/Security: how resistant it is to cyberattacks.
• Reliability: how much confidence you can place in its functions.
• Survivability: how well the system performs under poor conditions.

Design

• Correctness: how well the system conforms to requirements.
• Verifiability: how easy it is to verify the system's performance.
• Maintainability: how easy it is to repair the software.

Adaptation

• Expandability: how easy it is to upgrade or expand capability.
• Interoperability: how easily it interacts with other systems.
• Flexibility: how easy it is to change.
• Portability: how easily transportable the system is.
• Reusability: how easily it can be converted for use with another system.

Who Is Responsible for Preparing Non-Functional Requirements?

Functional requirements can live in a Functional Requirements Document (FRD), while a Product Requirements Document (PRD) combines functional and non-functional ones. Non-functional requirements are usually defined by developers, software architects, and other technical experts, and the PRD is typically prepared by the product manager.

Comparison Table: Functional vs. Non-Functional Requirements

Conclusion on Functional vs. Non-Functional Requirements

Your software needs both functional and non-functional requirements to perform at its best. The first set lets it run, the second elevates the user experience. It pays to work with a custom software team that documents both kinds meticulously, because thin documentation leads to a disappointing product or a decent one that blows past budget and schedule. We in Brocoders treat this requirements-gathering depth as the groundwork for every successful product we ship.

How to Write the Documentation

You now know the main elements of an SRS. The next step is putting them in order to create one cohesive document. We have built a template that addresses the requirements relevant to every party, the same one we use across our product development process.

Requirements engineering rests on four activities:

• Requirements elicitation (interviews with stakeholders and decision makers)
• Requirements analysis (checking they are consistent)
• Requirements documentation
• Requirements verification and validation (am I building the system right, and am I building the right system)

Requirements Engineering in the SDLC

To write an SRS you need a framework, and there are plenty of templates to streamline the process. There are also standards to follow when writing technical requirements. IEEE 830, for instance, is older but still widely used.

There is also an international standard, IEEE/ISO/IEC 29148-2018, which we have adapted for our needs. The examples below come from the Reqview tool, which we use to organize requirements documentation in line with that standard.

Another tool we use for requirements management is Confluence by Atlassian.

Product documentation can be separated into four parts:

1. Needs Document: describes high-level user needs via user stories.
2. SRS: the software requirements specification.
3. Tests: describes the test cases verifying functionality from the requirements.
4. Architecture: describes the architecture of the application.

In the examples below we show how to create the Needs, Architecture, and SRS documents. At a minimum, we suggest preparing a Needs document so it can be sent to potential vendors before you commit to building, which is a smart first move whether you are planning an MVP development effort or a full platform.

Needs Document

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1. Introduction

This document describes the high-level functional requirements of the software.

1.1 Purpose. An informational section describing the purpose of the document. A common opener is "The purpose of this document is to describe the software that is going to be built for..."

1.2 Project Scope. Briefly describe the scope of the product. For software used to create an SRS (such as the Reqview tool), it might read like this. Users should be able to:

• Record requirements specifications
• Use custom attributes to manage requirements
• Set up requirements traceability and browse the matrix
• Review and comment on requirements
• Filter and search for requirements
• Import requirements from Excel and MS Word
• Export requirements to PDF, HTML, DOCX, XLSX, or CSV
• Print requirements specifications
• Analyze requirements coverage and change impact

1.3 User Roles. Identify user roles for the product, and for each role describe a typical user. Consider creating personas with real names, each described well enough that the whole team feels they know the persona.

Here is a user roles definition from Reqview:

And here is an example from our own product documentation:

2. Product Functions

2.1 User stories. We use user stories to describe a product and its functionality, and for easier navigation we group them into "epics." To write a user story, set these attributes:

• Heading: a short story name
• As a(n): the type of user
• I Want: a goal
• So That: a reason
• Acceptance Criteria: how the story should be verified
• Priority: "High" for fundamental features, "Medium" for important features with a short-term workaround, "Low" for features needed in a later release
• Risk: "High," "Medium," or "Low"
• Estimation: story points that give relative estimates of complexity, effort, or duration
• Status: "New," "Planned," "Implemented," or "Verified"

User stories example from Reqview:

User stories example from Confluence (source: Atlassian documentation):

2.2 User statuses flow. Sometimes you need to show a flow using diagrams, as in this user status flow:

And here is a Deal/Order creation and status flow:

3. Constraints

Here you describe constraints that act as global requirements, such as application speed or limited development resources.

Example from Reqview:

Architecture Document

1. Introduction

2. Architecture

It can be described this way.

Overall architecture. Operates with six types of users who access the system through three interfaces:

• Web application
• Admin panel (web application)
• Mobile application (both Android and iOS)

Staging Environment. Hosted on Brocoders AWS resources and handled by the local team. The infrastructure includes a Redis instance for delayed jobs, an Amazon S3 bucket for system files, and general instances for the admin panel and web app.

Production Environment. Hosted on the client's AWS resources, set up in the same manner. For platforms that need to serve many tenants from one codebase, this is also where you plan multi-tenant SaaS architecture.

3. References

Lists the SRS and any documents or websites the document refers to.

SRS Document

1. Introduction

1.1 Purpose. The main purpose of this document is to provide a working example of a Software Requirements Specification based on the ISO/IEC/IEEE 29148:2018 standard.

1.2 Scope. As with the Needs Document, describe what problem the software solves and how it will be used. Users should be able to:

• Record requirements specifications
• Use custom attributes to manage requirements
• Set up requirements traceability and browse the matrix
• Review and comment on requirements
• Filter and search for requirements
• Import requirements from Excel and MS Word
• Export requirements to PDF, HTML, DOCX, XLSX, or CSV
• Print requirements specifications
• Analyze requirements coverage and change impact

1.3 Product Perspective. Describe how the product relates to other elements of the system, for example whether it is part of a larger system. You can include requirements for user interfaces, system interfaces, hardware interfaces, software interfaces, communication interfaces, and memory constraints.

1.3.1 System Interfaces. List each system interface and identify the software functionality that accomplishes the system requirement. For example: the application runs on the latest version of Chrome or Firefox on Windows, Linux, and Mac.

1.3.2 User Interfaces. List the logical characteristics of every interface between users and the software, for instance GUI standards and sample screen images.

1.4 Product Functions. Link this section to Section 2 of the Needs document (user stories).

2. Requirements

Product functions are summarized in Section 2 of the Needs document (user stories).

2.1 Functions. This section describes functional requirements. Every function should link to the Needs, Tests, and Architecture documentation, and it is often convenient to link it to a task in Jira.

Here is how it looks in the Reqview tool:

2.2 Usability Requirements. Define usability and quality-in-use requirements for the system, including measurable effectiveness, efficiency, satisfaction criteria, and avoidance of harm in specific contexts of use. A usable interface design should support these goals for its primary users:

• Efficiency: few setbacks and quickly achievable goals.
• Intuitiveness: an easy-to-learn interface with simple navigation, where headings, buttons, and error messages are easy to understand.
• Low perceived workload: the interface feels simple to use rather than intimidating, frustrating, or demanding.

2.3 Performance Requirements. Performance requirements define how well the system accomplishes certain functions under specific conditions, such as response speed, throughput, execution time, and storage capacity. They are usually based on supporting end-user tasks and are key to the design and testing of the product. Examples include:

• Database requirements
• Design constraints
• Standards compliance
• Software system attributes

3. Verification

Verification tests are specified in the [TESTS] document.

4. Supporting Information

Provide the information and define the terms needed to understand the document. Define abbreviations and acronyms, provide diagrams and models, and create a numbered list of any TBD occurrences.

5. References

Include the following for references:

• A complete list of all documents referenced elsewhere
• Each document identified by title, report number (if applicable), date, and publishing information
• The sources from which the references can be obtained

Once you have completed every section of the SRS, get it approved by the project's key stakeholders. Make sure everyone reviews the most recent version.

How AI Helps You Write an SRS or PRD

Requirements work used to be the slowest part of any project. Workshops were followed by days of manual note-taking, email clarifications, and document assembly, and even then the PM's notes, the analyst's interpretation, and the developer's understanding often drifted apart. AI has compressed that whole cycle, and the same shift is reshaping every phase of the agile software development life cycle. Here in Brocoders, discovery work that once took 4 to 8 weeks now produces the same foundational documents in 1 to 2 days.

The shift starts with a single decision: the workshop transcript becomes the source of truth. Every discovery session is recorded and transcribed in full, so the documentation is grounded in what the client actually said rather than someone's memory of it. Anton, one of our project managers, describes the change:

"Everything comes from the transcript. The client explains their business, we discuss functionality, all decisions get captured. Then we feed all of that to AI, and the documentation writes itself, correctly, because it's grounded in what was actually said."

From that one transcript, we run AI agents in parallel to draft the foundational documents. A product-owner agent produces the PRD (Product Requirements Document): user stories, business requirements, and user flows that bridge client language and development language. A software-architect agent produces the SRS (Software Requirements Specification): the technical stack, architecture, and integration requirements, kept deliberately concise so it defines what to build without re-explaining patterns the team already knows. All documents are then cross-audited against each other and against the original transcript, and any conflict is resolved by returning to the transcript. By the time developers open Jira, the epics and sprint structure are already built from the same transcript the client signed off on.

Concretely, AI helps at six points in the requirements process:

• Transcribing and structuring workshops so nothing said is lost.
• Drafting first-pass user stories, acceptance criteria, and user flows for the PRD.
• Generating a first-draft SRS with functional and non-functional requirements mapped to those user stories.
• Cross-checking the PRD, SRS, and design docs for contradictions and gaps.
• Converting approved requirements into Jira epics, sprints, and tickets.
• Flagging ambiguous language so vague terms get replaced with measurable criteria.

Best practices for AI-assisted requirements

The tools are powerful, and a few practices keep the output trustworthy. Many of these line up with what the broader field settled on through 2026:

• Keep one source of truth. Anchor every document to the recorded transcript or a confirmed brief, so the AI grounds its draft in real decisions instead of plausible guesses.
• Treat the spec as a living document. Update it whenever a decision changes, so it stays the ground truth for both the team and any AI development agents that read it (O'Reilly).
• State non-goals positively. Spell out what is out of scope for this phase. An agent that does not see "authentication is out of scope for phase one" may add it anyway, because most apps have it (ChatPRD).
• Blend PRD and SRS thinking. Use PRD-style user context so the model optimizes for the right outcome, and SRS-style specifics (database, APIs, constraints) so it can produce correct technical decisions.
• Phase the requirements. Break work into sequential phases with clear dependencies and testable outcomes, which both humans and coding agents follow more reliably.
• Match detail to complexity. A trivial task does not need an exhaustive spec, while an OAuth flow with token refresh and error handling does.
• Always validate by eye. Every AI draft gets a human pass before it ships. "It looks plausible" is not a standard we accept, because a model can skim a long document or hand back something confident and wrong.

Use AI as a first-pass reviewer

One of the highest-value uses of AI in requirements work is catching gaps before a document reaches a costly human review. Uber's product teams built a first-pass AI PRD reviewer that does this: it assembles context around a draft PRD (linked documents, prior experiments, metric definitions), classifies how deep the review needs to be, then scores the document across six launch-readiness dimensions and returns a scorecard with a single "start here" fix. It is designed to augment senior judgment rather than replace it (Uber Engineering).

You can apply the same pattern to an SRS or PRD on any project. A strong first-pass review checks six things:

• Problem clarity: is the problem real, evidenced, and worth solving now?
• Success definition: is there a primary metric with a baseline and a target, plus guardrail metrics?
• Scope and decision-readiness: are the boundaries of version one explicit, with no unresolved open questions?
• User impact and edge cases: does it hold up across user segments, geographies, and failure states?
• Dependencies and cross-functional risk: are downstream systems, legal, compliance, and ops impacts named?
• Rollout and validation: is there a release plan, a rollback plan, and a credible way to measure success?

A few hard boundaries make the verdict decisive. Treat the document as not ready when it has no defined success metric, no baseline or target for that metric, an ambiguous primary user, or no rollback plan for changes that touch payments or core user flows.

Here in Brocoders we run a version of this discipline by cross-auditing the PRD, SRS, and design documents against each other and against the transcript, and by asking the model to challenge its own output. Anton describes the habit:

"We ask the model to argue why the plan will fail, not why it will work. Then we decide for ourselves."

Because the same transcript also drives the backlog, the handoff stays clean:

"We don't write tickets manually anymore. By the time the development team opens Jira, the sprint structure is already there, built from the same transcript the client signed off on." Anton, Project Manager at Brocoders.

The takeaway is steady: AI removes the blank page, the manual assembly, and the avoidable gaps, while experienced people still own the judgment about what the product should be. That balance is exactly how we run requirements across our product development process.

SRS Design Guidelines

Now that you know the general structure of an SRS, you are well on your way. A few design guidelines will help keep your document as clear as possible:

• Include plenty of diagrams and models, since they make processes easier to understand.
• Avoid ambiguity, so the parties can sidestep endless discussion and doubt. A formal peer review is a reliable way to surface ambiguity.
• Pay attention to sequence. One section should not conflict with another, so use the same terminology and keep a consistent format.
• Use accurate, precise language. Replace "the app needs to be released as soon as possible" with specific dates, figures, and goals.
• Create a glossary, especially when you rely on internal definitions.
• Save the history of changes, so anyone can trace edits back to the first version.
• Assign each requirement an identifier so it is easy to trace in the documentation.
• Use critical thinking to prioritize the product's main functions.
• Focus on the customer, keeping a clear portrait of the average end user.
• Keep the SRS flexible enough to be updated as the project evolves.

Summing Up

SRS documents can be long, and they look complicated at first. Follow the template above and you will find that creating one is very manageable. The payoff, sharper communication and aligned goals, easily outweighs the effort of drafting and approving the document.

Here in Brocoders we create an SRS for every project we take on, and it is the first step in turning an idea into a working product. If you want to see how that groundwork carries through to a finished platform, explore our SaaS product development work and our SaaS case studies. Reach out today and we will walk you through our software development process.