How To Write a List of Requirements for a New Application

Did you know that fixing a defect during the maintenance phase can cost up to 100 times more than addressing it during the requirements phase? This striking insight from the Systems Sciences Institute at IBM perfectly illustrates why creating a clear and detailed Software Requirements Specification (SRS) is a non-negotiable step in app development.

Think of the SRS as the blueprint for your mobile app. It’s more than just a document—it’s your story, crafted to guide developers, stakeholders, and designers toward the same vision. With every detail defined, you reduce misunderstandings, save costs, and speed up the journey to a flawless final product.

In this article, I’ll take you through:

• What an SRS is and why it matters.
• The critical differences between functional and non-functional requirements.
• A step-by-step guide to writing a bulletproof SRS document.
• A practical example to help you visualize how it all comes together.
• Real-world use cases from successful mobile applications.

What Is Software Requirements Specification?

A software requirements specification (or a list of requirements) is a formal document that outlines the scope, objectives, and functionalities of a software system.

A list of requirements serves as a communication bridge between business stakeholders, developers, and designers, ensuring alignment on what the software is meant to achieve. By detailing both the business goals and technical specifications, an SRS provides a clear roadmap for building a system that meets user and organizational needs.

From a system perspective, an SRS defines the functional and non-functional requirements, setting expectations for performance, security, and usability. It also addresses transitional requirements, ensuring a seamless migration from the current state to the new system. This comprehensive approach reduces ambiguity, mitigates risks, and ensures all stakeholders are on the same page throughout the software development lifecycle.

The Difference Between Functional and Non-functional Requirements

Understanding the difference between functional and non-functional requirements is key to ensuring a well-rounded and successful software development process. Here are

Functional Requirements

Functional requirements define what the software must do to meet its purpose. These are the specific tasks, processes, or operations the system needs to perform to deliver value to the end-user.

For example, in a mobile banking app, functional requirements for features may include the following:

• Account management: The app should allow users to view their account balances and transaction history.
• Funds transfer: Users must be able to transfer money between accounts or to external beneficiaries.
• Login authentication: The system should support multi-factor authentication to ensure secure user access.

Functional requirements are often task-oriented and directly tied to the user experience. They specify how the software interacts with users and external systems, serving as the foundation for system functionality.

Non-functional Requirements

Non-functional requirements, on the other hand, describe how the system performs under certain conditions rather than what it does. These focus on the quality attributes of the system, ensuring a reliable, efficient, and user-friendly experience.

In the same mobile banking app, non-functional requirements for system attributes may include the following instances:

• Performance: The app must load the account overview page within 2 seconds, even during peak usage hours.
• Security: All data transmitted between the app and servers should be encrypted using the latest protocols, such as TLS 1.3.
• Scalability: The app must support up to 1 million concurrent users without degradation in performance.

While functional requirements focus on actions and capabilities, non-functional requirements define the environment and standards that enable those functions to operate optimally. Both are equally critical to the software’s success, working together to create a complete and reliable application.

Read also about the role of business analyst in fintech products detailed in another blog post by DashDevs.

Why Writing an Application Requirements Document is Important

SRS ensures that all stakeholders have a shared understanding of the project’s goals, functionalities, and constraints. Without a well-crafted software requirements specification, projects are prone to miscommunication, scope creep, and costly delays. According to a report, clear requirements are a factor in the success of 70% of projects, underscoring the value of this critical step in the development process.

With these benefits, a well-structured SRS not only saves time and money but also builds a framework for long-term business success.

How to Write a Software Requirements Specification Document

Creating a Software Requirements Specification document is a meticulous but vital process. A clear SRS ensures clarity, minimizes risks, and aligns all stakeholders while serving as the blueprint for your software project. Here’s a detailed, enhanced guide to crafting an SRS document:

Step #1: Create an Outline

Before diving into the specifics, establish a clear structure for your document. A well-organized outline improves readability and ensures all critical areas are covered.

What to include:

• Introduction: Purpose, scope, and audience.
• System description: High-level overview, constraints, and assumptions.
• Requirements: Functional and non-functional.
• Supplementary details: Dependencies, risks, and future considerations.
• Approval section: Space for stakeholder sign-offs.

Pro tip: Use consistent section numbering (e.g., 1.1, 1.2) to make referencing requirements easier during the development process.

Step #2: Define What the Purpose of Your Software Is

This is where you lay out the foundation of the project by answering questions such as: What problem does this software solve? Who benefits from it? Why is it needed?

How to write it:

• Define the main objective. For example, “The purpose of this software is to provide an intuitive appointment management system for small businesses.”
• Highlight benefits, such as “Reduce no-shows by 30% through automated reminders and a user-friendly scheduling interface.”

Pro tip: Relate the purpose to business outcomes, such as increased ROI, operational efficiency, or market competitiveness.

Step #3: Give an Overview

The overview should provide a high-level summary of the software’s goals and capabilities.

What to cover:

• Target audience: Specify user groups, such as customers, administrators, or third-party integrators.
• Scope: Define boundaries. For instance, “The system will focus on scheduling and analytics but will not include accounting functionalities in the initial phase.”
• High-level functionality: Briefly introduce major features, like “Customer booking, automated reminders, and performance reporting.”

Pro tip: Include real-world scenarios. For example, “A restaurant manager can set availability, and customers can reserve tables via the app.”

Here is an example of an overview from one of our SRSs—verifier sign up.

Step #4: Describe Functional and Non-functional Requirements

The requirements section is the heart of your SRS. Distinguish between the two types for clarity and focus.

Functional requirements:

Specific tasks the system must perform.

• Example 1: The system must allow users to reset their passwords using an email verification link.
• Example 2: Administrators should be able to generate monthly usage reports in PDF format.

Non-functional requirements:

Define the quality and performance of the system.

• Example 1: The application should handle up to 10,000 concurrent users without performance degradation.
• Example 2: The system must comply with GDPR regulations for data privacy.

Pro tip: Use a prioritization method like MoSCoW (Must Have, Should Have, Could Have, Won’t Have) to rank requirements, making it easier to plan and manage scope.

Step #5: Add User Stories and Acceptance Criteria

Now, we integrate user stories and acceptance criteria. User stories are an essential part of agile development and should be crafted with the end user in mind. A user story defines a specific feature or functionality from the user’s perspective, highlighting the value it will bring to them.

For example:

• As a user, I want to receive real-time notifications about my medical insurance status so that I can make informed decisions.

Alongside user stories, acceptance criteria should be included. These are clear, measurable conditions that define when a user story has been successfully implemented.

For example:

• The system must send a notification within 5 minutes of any policy status change.

These criteria ensure that all team members—developers, testers, and product owners—have a shared understanding of success. They serve as a benchmark for validating functionality and verifying that the software meets user needs and business goals.

Here is an example of our acceptance criteria:

Step #6: Add Supplemental Details

This section provides additional information that ensures smooth development and sets realistic expectations.

What to include:

• System assumptions
• Dependencies
• Constraints
• Future Considerations

Pro tip: Add diagrams like flowcharts, user interface mockups, or data flow diagrams to visually clarify complex processes or architecture.

Step #7: Get Approval

Finalize the SRS by getting feedback and approval from all stakeholders. This ensures everyone is aligned before development begins.

Steps to follow:

1. Distribute the SRS: Share it with developers, project managers, and business leaders.
2. Hold a review meeting: Present the document, address questions, and make adjustments as needed.
3. Incorporate feedback: Ensure all comments and concerns are resolved.
4. Sign off: Obtain formal approval from key stakeholders and log their signatures.

Pro tip: Use collaborative tools like Jira, Confluence, or Asana to streamline feedback collection and version control.

By taking a structured and detailed approach to writing your SRS, you lay the groundwork for a streamlined development process, better stakeholder alignment, and a higher likelihood of delivering a product that meets its intended goals.

Consider also our article on how to conduct a Discovery Phase in fintech projects and why it matters.

How We Write a List of Requirements For a New Application

At DashDevs, we understand that a well-organized SRS is critical for the success of any project. It ensures clarity among all stakeholders and serves as a guide throughout the development process. Here’s how we approached the SRS for two key projects—Inablr and Muchbetter—and why it was essential to their success.

Case #1: Inablr Investment Platform

Inablr is a unique platform designed to make sovereign bond trading accessible to individual investors. It allows users to split large sovereign bonds into smaller, more affordable units, lowering the starting investment amount and opening up a market that was traditionally reserved for large institutional investors. This innovative approach enables individual investors to participate in the sovereign bond market, which would otherwise be out of reach.

How we wrote the SRS for Inablr: For Inablr, the SRS focused on defining the key features that would drive the platform’s success, such as ensuring seamless transactions for bond purchases and enabling real-time trading. We identified the following user stories from both individual investors and institutional participants to ensure that both could benefit from the platform’s functionality:

• As an investor, I want to buy smaller bond units to diversify my portfolio without making a large upfront investment
• As a platform administrator, I want to manage bond listings and ensure security for every transaction

These user stories were accompanied by acceptance criteria that defined clear, measurable goals, such as transaction speed, platform security, and ease of use. The SRS ensured that every feature, from user interface design to backend processing, aligned with the vision of making sovereign bonds more accessible.

Why SRS was important: The success of Inablr depended on its ability to offer an innovative solution that appealed to a broad range of investors. The SRS helped define the platform’s key features and ensure the project met regulatory requirements and user expectations, making it a secure and seamless investment tool.

Case #2: MuchBetter E-Wallet & Payment App

MuchBetter is an innovative e-wallet app designed for secure, fast, and convenient money transactions, with a special focus on the gaming industry. Preferred by global gaming sites, MuchBetter allows users to store, send, and receive money securely, offering a practical alternative to traditional payment wallets like Neteller, Skrill, Entropay, and Ecopayz. It is widely accepted by high-street retailers and offers free, easy transactions for friends and family.

How we wrote the SRS for MuchBetter: For MuchBetter, we concentrated on the security and performance aspects, which are essential for user trust in financial transactions. The functional requirements included seamless money transfers, real-time transaction updates, and secure user authentication methods like biometric login. We also defined user stories such as:

• As a user, I want to securely transfer money to a gaming site instantly without high fees.
• As a retail partner, I want to ensure transactions are processed quickly and securely when customers use MuchBetter.

In addition to functional requirements, we also focused on non-functional requirements, such as high security, scalability, and integration with various payment systems, ensuring the app could grow with user demand while maintaining a top-notch experience.

Why SRS was important: MuchBetter’s success hinged on delivering a fast, secure, and user-friendly experience, particularly for the gaming community. The SRS helped define and document clear specifications around security, scalability, and functionality, ensuring the app met industry standards and delivered a high-quality service to users. This ultimately positioned MuchBetter as a trusted solution in the competitive payment market.

Wrapping up

In conclusion, a well-defined list of requirements for a new application is essential to ensure the project meets business objectives and user expectations. A solid foundation of clear and comprehensive requirements minimizes risks, reduces rework, and keeps the development process on track.

At DashDevs, we specialize in crafting detailed software requirement specifications (SRS) that guide the development process, helping you stay aligned with your goals and deliver a high-quality product. Whether you’re building a mobile app or a complex system, our team can help you document and define requirements for a seamless, efficient development journey.

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