How to Prepare App Requirements Document

Rating — 4.7·13 min·July 27, 2023
How to Prepare App Requirements Document
How to Prepare App Requirements Document
What is the app requirements document? Why do your team and your project need it? Find the in-depth answers here and learn how to present your idea and expectations in the best way.
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It’s a long way to the top once you decide to build a market-leading mobile app. It takes time, money, and dedication to take your idea from the moment it gets to your mind to the day when it’s finally live on app stores.

But what if, at some point, your idea deviates from a defined success course? Or what if your app development partner gets you wrong? Or what if you lose the clear vision of how to hit the target goals?

The mobile app requirements document is one of the tools not to lose your idea, features, and uniqueness in a daily routine, present your concept to your partners and define steps to reach the expected results. This document is an irreplaceable component of a startup discovery phase and a reliable source of information about the product for all the parties involved in development.

Build it correctly – and get closer to your goals.

Build it at the dawn of your business – and discover more channels to grow, avoid misunderstanding and find ways to cut costs.

The application requirements document answers the question about WHAT your software will do. And in this article, you’ll learn HOW to write the app requirements document.

What’s the app requirements document?

There are several answers to this question:

  • App requirements document is a document describing all the nuances related to your app development, from the moment you decide to build an app to the successful release;
  • This is the document that brings together the app’s purpose, specifics, features, and information about how your app will serve users’ needs;
  • This is a detailed description of an existing problem and its solution;
  • This is information about the technical aspects of the project, user flow, and key features.

App requirements document is sometimes called the software requirements specification. In general, the document answers two critical questions:

  • What can the app do?
  • How is the team going to build the app?

5 reasons to build app requirements document and how it can save your business

If you still hesitate is app requirements document makes sense for the project, check several hot reasons to start to build it:

reasons to build app requirements document

1. Clarified expectations

You state your requirements and expectations accurately. Thus, you can expect the delivered project to meet them precisely.

2. Team awareness

App requirements provide essential information for the entire team:

The Role

Why use the app requirements document?

Product owner

Describe the project

Confirm that requirements reflect the business needs

Project manager

Develop the scope of work

Cut project into iterations

Track development progress

Business or system analyst

Confirm the existing demand in the target market

UI/UX designer

Design the application

Software developer

Understand the app's purpose

Create the app's architecture

Code the solution

QA engineer

Verify if the developed functionality meets business needs

It is essential for attracting investors and serves as a guiding light for project development and testing teams.

3. Accurate estimation

Software engineers can estimate the effort needed to convert your expectations into app features. The more thoroughly you describe the idea, the more accurate estimation you get.

Each project is unique; thus, no development agency can provide you with accurate sums and estimations before requirements are presented. However, the volume of efforts is proportional to the budget. And with well-described app requirements, you get closer to more precise estimates and fewer budget-related risks.

4. Cost optimization

The development team, fully aware of app requirements, may come up with a solution on how to minimize unnecessary cost and deliver critical features in the first turn. Your engineering partner may help you to decide on the features necessary to validate the idea. There’s no need to invest thousands of dollars if you’re not sure whether certain functionality is needed or not.

App requirements allow identifying possible ways to minimize development cost. For example, if your app requires online chat, you can either invest thousands of dollars to build a custom solution from scratch or integrate the existing solution and invest several dollars per month.

Besides, detailed app requirements development is the method to save on software redesign or redevelopment. Clearly described expectations mean less changes.

5. Smooth scheduling

Broken project deadlines may lead to additional costs and longer time-to-market. In general, that’s the feature of ineffective management and the consequence of poor app requirements.

However, if built correctly, app requirements help create a smooth, optimized workflow and set reasonable time frames and deadlines. It gives you predictability and allows accurately planning project sprints.

App requirements development is a sort of project kick-off. Built wisely, they contribute to your product’s growth, success, and further maintenance, optimize cost and align your plans with development sprints.

When you need (and when you don’t need) app requirements document

If you still hesitate whether you need to dive deep into requirements, make a final decision with these two points:

  • You don’t need to invest in the app requirements document if your product takes not more than 1-2 weeks of coding;
  • You don’t need to invest in the app requirements document if nothing more than a single developer’s efforts are required.

So, if your product is something as small as the simplest prototype, you can build it without the requirements’ document. If there is only one person responsible for coding (or design, or any technical task), you probably can avoid requirements development, too.

However, in the following cases, a requirements document is a must:

  • Estimated development time takes more than a month;
  • More than one person contributes to the product;
  • You plan to monetize the application.

So, what’s your case?

Functional vs. technical requirements: know the difference

Looking for information about app specifications, you may come across two separate concepts: functional specifications and technical specifications. Don’t worry, we’ll tell you how to build both. But first, let’s make things clear:

  • Functional specifications explain how the product will work;
  • Technical specifications describe another perspective – the engineering side of software development.

Functional requirements don’t explain how you will build a product. Instead, they tell how the user will use it, how it works and serves real needs. To construct the functional specs document, none to minimum technical awareness is required.

The technical specification is something different. In this document, a software developer or team leader needs to add the detailed info of data types used for your product, its structure, models, dependencies, and other tech specifics. To complete this document, a strong technical background is needed.

Combined and enhancing one another, functional and technical requirements build a detailed, well-described app requirements document.

How to build app requirements document

Now, let's see how to turn your expectations into an explicit document.

Build the ground

Think over your idea and make sure there are no blind spots for you at the moment. Take a look at similar applications: what are their strengths and weaknesses? Does your idea stand out in the competition?

And are you ready to turn the idea into a document describing what exactly to do?

And what's the most important, do you have enough time to build a document yourself, or should you delegate it to the development team?

App requirements document builds the ground for your app’s spotless design and functionality. To get the most out of this document, you need to contribute time and energy, make it understandable and present it to the team you work with. It is critical to describe the expectations as thoroughly as possible, predict developers’ questions, and provide them with answers before they start working on your app. It is vital to understand the tech specifics, define technology stack and make the document clear for the engineers.

Behind the document, an avalanche of work is waiting to descend. Thus, if you are tight on terms or have no free time to invest in app requirements document development, consider delegating it to a discovery team.

Choose the format

Once you’ve collected some essential details about your future product, it’s time to decide how you’ll provide your team, partners, and investors with it. Appropriate document format is the key to clear understanding and, as a result, a product that meets your requirements.

data formats in app requirements document

  • Functional specification

It describes what and how a product should do with simple bullet points. Each point should be comprehensive and detailed. Here, you define the general idea, user journey, and overall app purpose.

For instance, if you want to build a delivery app, do you plan to use GPS-based features? Would you integrate payment functionality? What payment gateway would you like to choose? What platform, tools, and plugins your team is going to work with? Every tiny detail matters. Thus, to build a requirements document correctly, you need to cooperate with an engineering professional, able to describe technical specifications.

  • User stories

Unlike the functional specification, user stories are less formal and more user-oriented. This is the document describing your app from a user’s perspective.

Among other aspects, user stories explain why exactly users would want to choose your product. This format is quite understandable, readable, and flexible. Enhanced with technical specifications, acceptance criteria, and prototypes, user stories may turn to steps in a development workflow.

At this stage, it is essential to describe them correctly and make sure technical details are precise.

  • Visual formats

These are simple sketches and wireframes. Set of screens describe needed functionality and user interface in the best way. Their sequence in the sketch easily represents relations and links between screens. It’s a handy way to explain to both your partners and your engineering team what you would like to get at the endpoint.

  • Mix it up!

Try different formats to develop the best version of your app requirements document. Take advantage of each format to demonstrate how you see your product and its realization. Enhance text with visuals and add descriptions to wireframes so your plans and vision were clear.

Put together

Now, it’s time to convert your thoughts and ideas to a usable document. Implement the following structure:

Part I - Application overview

Start with the basics. Step by step, guide the reader through your app’s general idea, objectives, and purpose. Explain the app’s role in your business and existing demands.

  • Introduction

What is your app about?

Are you about to build the next generation on-demand app or fit the existing market gap? Tell the reader the name of the app and provide a general explanation.

  • Objectives

Why do you do this?

How does your app serve business needs?

Here, describe what business goals you’d like to achieve with this app. Is this an automation tool for an existing business? Or a promising startup? Tell about the current situation in your company and describe how your app will improve it.

For example, you run a marketing company and need a tool for data visualization. The app you plan to build will help you present information to your customers, deliver better results and increase your income.

Put down the objectives and think about why exactly you need to launch this app right now. Either if your company demands it, or there’s a gap in a local market, tell about it!

  • User roles

Why do users need your app?

How will the users benefit from your app?

Think over the user persona. Who are your users? How old are they? What’s their location, education, and occupation?

How exactly are they going to use your app?

For example, if you build a two-sided marketplace, it is very likely you will create it for service providers and customers. Describe the ICP and get one step closer to users’ demands satisfaction.

  • Interaction with other systems

How the app relates to other systems, both internal and external?

This section is essential for business owners. If you run a small, medium, or enterprise business, your application may be a part of an existing system. For example, you run a business website and would like to start selling your brand T-shirts. In this case, you add an eCommerce module to the existing system. Describe what integrations you need and how the improved system may look like.

Part II - Functional and technical requirements

Here, develop user stories and enhance them with descriptions and acceptance criteria. Representing data in such a format, you make it understandable and clear for all team members.

  • App’s features

What exactly does the app do?

Think carefully about must-have features and include them here. Use the detailed description and wireframes your app should use in the future.

Particular attention goes to security, administration, and reporting features. Security features define how you plan to encrypt and protect user data, administration functionality helps to manage relations between app's users and provide technical support, and reporting is necessary for you to be fully aware of users behaviour. State your requirements for these features accurately and avoid possible troubles in the future.

  • Tools and technologies

Which tools will the engineering team use?

The block is devoted to frameworks and technologies. To achieve the best results and the most precise description, engage a software development representative, or a software architect, to this block. Build a table describing a particular component of your app and the tools needed to build it.

For example:

App's component



HTML, CSS, JavaScript, Angular/ React.js/ Vue.js


PHP (Laravel)/ Node.js

Cloud integrations




  • Scope of work

What are the planned project phases?

Define how much time you plan to invest in each particular component of the app development process. App requirements document development is the component of a project discovery phase, which usually takes two to four weeks. 

After that, you will start an MVP development. According to Agile methodology, you need to cut MVP development to two-week iterations. Each iteration should end up with a new release, and each time you get a better version of your product.

Prioritize critical features and add them to initial sprints. Step by step, build a plan for all features development.

  • App’s performance

What are the requirements for page or file load?

Define performance requirements. Try to be as specific as possible.

As you know, users are ready to wait not more than three seconds for a web page to load. So state that your app page should load in less than three seconds, not as quickly as possible.

These are the critical points for your document. You may extend this list with usability and administration and safety requirements, security specifics, or concurrency requirements. It depends on your particular case. To clarify what else to add to the app requirements document, consult with your development partner or a development service provider.

Part III - Appendix

All details that don’t fit the main section, like additional documents, wireframes, and possible assumptions, belong here.

Present and ask for feedback

When you have everything ready, it’s time to demonstrate it to your team.

Remember to check the effectiveness of the app requirements document. Ask for feedback from:

  • Your team (management, engineering, QA)
  • Stakeholders/ investors

Ensure that everyone involved in the product development and growth process shares the same vision of product goals and implementation.

Once you have approval, you can start working on a product.

Bonus section: 5 main characteristics of a useful app requirements document

Your document must be:

  • Explicit

To minimize misunderstanding, make your document easy to read and understand. Re-read it and try to simplify if possible.

  • Measurable

The document’s components should be measurable. Set time frames or decide on other methods to ensure the document’s clearness and effectiveness.

  • Complete

The document you work on MUST include all information related to product development. From authorization screens to a successful checkout - all features and requirements must be included.

  • Consistent

Make sure there are no conflicts between different requirements.

  • Accurate

Avoid statements like:

  • “This app should be better than Facebook”
  • “I want it to load in a blink of an eye”
  • “The UI should be impeccable”

And replace them with:

  • “This is the online social network for the students of a local university”
  • “The page load time should not exceed two seconds”
  • “The user interface should include such components as...”

Describe your expectations precisely to avoid confusion in the future.

features of app requirements document

Final thoughts

App requirements document or product requirements specification is an essential component of a software development project. It helps to clarify your own vision and describe it in detail to the stakeholders, partners, and development team.

Without a clear, detailed, and technically powered document, it is impossible to answer the following questions:

  • How long will the development process take?
  • What are the features of your product?
  • How to build these features?

App requirements document gives you predictability and allows you to calculate app development cost more accurately.

Invest in the app requirements document and get the product that meets your expectations and budget.

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