Writing an App Development Requirements Document: Step-by-Step Guide + Free Template
To build the app fast and smoothly, you need not only to plan everything but, what’s even more important, effectively communicate your ideas and vision to the team. What can help you with this task is an app development requirements document. We’ll provide you with the algorithm for creating this document and share a ready-to-use mobile app requirements template, so there will be no problems for you even if you’re not much of a techie.
App development requirements document 101
We’ll start with a quick overview so that you’ll learn what this document is, why you need it, and more. If you’re already familiar with all that stuff, we’ll just make sure we’re on the same page.
What is an app development requirements document?
An app development requirements document is a document describing the business logic, features, technical details, restrictions, and dependencies of your future app. This document works as guidance for your development team. It is not necessarily static, especially in agile development: the details can be added into it in accordance with development progress or any other changes.
Further and in other sources, you can come across the following terms: mobile application documentation, mobile app specification document, product requirements document (or simply PRD), and similar. Don’t worry: they all mean the same thing.
Why you need a PRD
Having a PRD is crucial for all who are involved in the development of the app: product managers and stakeholders, developers, designers, and others. It helps to:
- make sure that everybody involved in the project have the same vision;
- communicate the idea of the product to other collaborators (such as support, marketing, or sales teams);
- get a basic understanding of the development stages.
The product requirements document is also a starting point for creating detailed technical documentation for mobile applications, mobile app design documents, and other specified documents for all the specialists involved in the development process.
Who writes a PRD
Usually, it is the product manager who writes mobile application project documentation. But in fact, a lot of specialists are involved in this process: first of all, development and UX/UI teams. They help in mobile app requirements gathering, planning, and more.
What should you include in your app development requirements document?
At Surf, we’ve been developing mobile apps for more than 10 years and we can say for sure what information is necessary for your team in their work. Basically, your mobile app development documentation should include at least business requirements documents (BRD) for mobile application, technical specification, and mobile app design documents. But you are free to add anything that will come in handy.
Business requirements
Product vision or mission. Strictly speaking, it’s not a requirement, but it describes the problem the app is created to solve, its value for the user, and thus — the core functionality of the app.
Example
‘Tinder makes being single more fun and rewarding by connecting people who may not have otherwise met in real life.’
Objectives. Your objective to build the app also affects it a lot: for example, it defines the type of the app in the first place and lots of its features.
The objectives of your app can be:
- sales (for example, if you build an e-commerce app);
- growing customers loyalty (you can incorporate a loyalty program in the app);
- communicating with users and engaging them, and similar.
Examples
50 000+ in-app purchases every month
1 000+ loyalty program members within the first year
User personas. Creating user personas is helpful not only marketing-wise: knowing for whom you’re going to develop the app, what their needs and expectations are, you’ll make it more user-friendly, more inviting, and loveable. For example, if you’re building an app for kids, you may want to reduce the amount of text in the interface; if you’re building an app for people with special needs, you should think of inclusive design.
When creating a persona, do not limit yourself to describing demographics, such as age, gender, occupation, and so on. You should also consider the user’s goals, struggles, habits, motivation, influences, skills, and similar.
Example
This is how a user persona for a home exercising app might look like.
Monetization model. There are several ways to monetize your app:
- advertising (placing ads in your app);
- pay per download (making users pay to download the app);
- in-app purchases (selling goods via the app);
- subscriptions and freemium (making a user pay for using the app or some features of the app respectively).
Technical requirements for an app
In this part of your app development requirements document, you’re going to write about how your app will be operating, on what platforms, what functions it will have, and more.
Type of the app. The type of the app defines its core functionality, and features needed. Your app can be of the following types:
- e-commerce app;
- content app (streaming services, education app);
- service app (booking hotels);
- communication app (messengers, social media);
- mixed or other.
To learn more about the apps of different types, and how they are built, check out our case studies.
Platforms. Choose whether your app should be for iOS, Android, or both (in this case, you can develop a cross-platform app). Also, it’s better to specify with which versions your app should be compatible. As a golden rule, your app should support at least the latest and next-to-last versions of the OS, but it’s better if it is compatible even with three- or four-year-old versions.
Example
All Android versions from 4.4 (KitKat) and up
Devices. One more important thing to specify is for what devices your app will be: smartphones, tablets, smart TVs, smartwatches, or maybe several categories. The amount of work depends on the devices you want your app to be run on. For example, if you want your app to work on tablets, you’re going to need extra UI versions for portrait and landscape orientation.
Feature list. It’s better to build an MVP of the app first, so do not try to include all the features you want to see in your app at once. Of course, you’re going to need some basic features, common for all the apps. They are:
- sign-up and sign-in forms;
- navigation;
- push notifications.
The exact feature list depends on the type of your app. For example, if you’re building an e-commerce app, it’s going to need:
- a cart;
- product cards;
- transactions history;
- purchase history;
- payments system integration, and the like.
Functional requirements. This is how you want things to happen in your app. For example, you can describe:
- what are the types of users and what each of them can do;
- how should authentication be performed;
- what functionality should a user profile include;
- what are transaction statuses and how they change (if you sell anything via the app);
- how the app will handle user errors, and so forth.
Example
The user profile screen is where a user keeps personal information: first name, email, telephone number, date of birth, and password. Personal information is collected initially during sign-up. In the profile, a user can change a password or update personal information. A user might be asked to verify profile information every six months.
Dependencies. You should also keep in mind external factors that can affect your app development. Those can be:
- third-party software you might connect your app with;
- requirements and restrictions of the platform or account;
- hardware on which the app will operate or will connect with, and others.
If there are any dependencies, add their documentation or any other information about them in your app development requirements document.
Example
RevenueCat for in-app subscriptions (documentation: https://docs.revenuecat.com/docs)
Design requirements
There are several basic things to add your mobile app design document:
- UX flow charts — to visualize the way a user interacts with your app;
- sketches of the screens;
- special interface requirements — for example, if you need a responsive design.
Also, you should describe:
- style of the app (informal, conservative, catchy, or similar.);
- color scheme (warm, neutral);
- typography.
If you have a brand book and want your app to align with the general design guidelines of your company, add it to your app development requirements document too.
Mobile app requirements gathering: step by step
If you don’t want to miss anything when creating an app documentation, follow these steps:
- Formulate the idea of your app, its vision, or mission. Keep in mind your target audience, the problem they are trying to solve, what your solution is and what advantages it has. To express your idea more precisely, you can use common business methods and techniques, such as the ‘Jobs to be done’ framework and its formula ‘When X, I want to Y, so I can Z’.
- Put yourself in your users’ shoes. Try to reconstruct the user flow: imagine what steps users make while exploring your app, what screens they see, how they act. Start with the main screen and the main flow, then think of secondary ones. Describe those steps and screens.
- Find references. Search app stores for the existing analogs of your app. List their features you like and dislike. Think about what features will be appropriate for your own app.
- Talk to the team. With the basic user flows description, and the list of features, you already have a basic mobile app documentation sample to discuss. Your team members will tell you if there is a technical possibility to develop the features you want, what the restrictions, risks, and dependencies are.
- Prioritize. Do not try to add all the bells and whistles to your app at once. Concentrate on the basic features that allow you to present an MVP soon.
- Polish up. With a better understanding of the mission of your app, its user flows, its features, and all the technicalities, as well as having a development roadmap, you can write a full-blown app requirements document. Add wireframes: even simple hand-drawn ones are appropriate.
Formats
It’s hard to find a universal app requirements document template developers like — so just choose the format that will allow you to be precise and comprehensible.
Functional specification document (FSD)
Functional specification document describes all the elements of the app and how they function. FSD usually includes:
- user roles and responsibilities descriptions;
- information about system dependencies;
- interface and its elements descriptions, interface diagrams;
- data flow diagram and connected issues, such as data collection, validation, backup, and so on.;
- integration requirements (API’s, data flow diagrams, and similar);
- report requirements (data elements and contents required, frequency, and so forth);
- error handling (the nature of the error, the scenario branch that led to the error, ways to handle it);
- authentication, authorization, and password issues.
Here is how an ecommerce mobile application documentation sample might look like if it was written in the format of FSD:
‘The ‘Main’ page is the page where all products are displayed. They are sorted by price, in ascending order. After clicking a product thumbnail, a user is redirected to the product page which displays the name of the product, its price, and description. A user can choose the needed size and color if available. After choosing the color and the size, a user can add an item to the cart.
User Stories
User stories are less formal than a functional specification document. They describe the product and its functionality from the point of view of a user, an ordinary person. Despite the simplicity, this method is pretty effective as it combines both business and technical requirements. On the one hand, user stories show what problem users have and how the product helps them to solve it. On the other hand, it gives a general understanding of the features and functionality the product should have technical-wise.
Example
As a user, I want to see not only the size chart of a T-shirt on its page but also width and length measurements in inches to make sure the T-shirt will fit and I won’t have to send it back.
Sketches and wireframes
You can visualize your idea of the product using sketches and wireframes. Even hand-drawn ones will come in handy as they will represent the functionality you want to see in your app. Thanks to it, your team will get an understanding of the amount of work they’ll have to do.
If you’re familiar with basic UX/UI principles and design tools, you can provide your team with an advanced concept of the app: with the screens in different states, and so on.
Mixed format
It’s a good idea not to limit yourself to only one format: often, you need a bit of each one to communicate your ideas more effectively. For example, you can start with a user story to provide your team with a better understanding of users, their problems, and pain points; then add some sketches of the UI and wireframes to show a user flow; and support UI elements with some explanations in the form of an FSD.
Mobile app requirements template
We’ve created a free mobile application specification template that is easy to fill out even if you’re not a technical specialist.
If you don’t feel like digging into all the technicalities and details, just contact us straight, answer a couple of questions about your project and we will do all the rest.
