You don’t see buildings raised without architectural plans, and this is exactly what a functional specification is for mobile and web apps. Without a proper plan, our construction will be laid upon doubtful foundations, exposing us to delays and the need for corrections in the future. So, what is a functional specification? What role does it play and how to prepare it? And can it be prepared without IT know-how?

What is a mobile and web app specification?

An app requirements document, or PRD (Product Requirements Document) constitutes the basis of a digital product. This document should be very precise in describing the entire functionality of the future app. Beginning with the idea and business objective, through characteristics of the target users ending with the program’s action scenario. You are surely aware that a lot of information must be collected even before preparing the specification, and this regards: the target group, competition or technology. A well-written PRD (Product Requirements Document) has no place for speculations.

Even the broadest description of the idea behind the app is merely an introduction to the functional specification. The document should cover any interactions of the user with the program. If you are not familiar with the basics of coding, you can use the so-called User Stories and be quite precise in explaining cases “what should happen, if...” in your own words. What is more, a specification should include nonfunctional requirements and information about the communicated databases and API used. Again, it is enough to point to the features and functions that are supposed to have their place in the program, like: data safety, ways of connecting with social media or payment methods. This way, a development studio will be able to estimate the necessary time and technology.

Coming back to the architectural analogy, a lack of specification may correspond to the request to build a house based on information about the area and the number of rooms. It doesn’t take too long to guess that the final effect may be significantly off from what we just might expect. Mobile and web PRD (Product Requirements Document) is like guidelines allowing your development team (regardless if internal or external) to understand the core functionality, prepare solutions, identify threats and prepare the next stages of production as early as the planning stage. In the case of an external software house and a fixed price, this is the only way to establish the precise dimensions of the budget. Underestimation and delays are usually the effect of a badly prepared functional specification (or lack thereof). It lies in the interest of both parties to plan every detail.

How to prepare the Product Requirements Document for a digital product?

Functional specification is not a form and does not go by one universal formula. The document should first and foremost be readable and meticulous. It is usually made up of a few basic elements: general description with our business goals, general operation of the program and the target user’s profile; technological requirements; functionalities; information regarding data format and file structure; app operation scenario; any other additional information. Each chapter should answer a series of topics, but it’s worth making the text concise. It’s not about creating an essay about how our app will save the world. The document should first and foremost be a practical tool for coders. That is why we will describe obligatory topics that should be covered in a mobile and web PRD (Product Requirements Document).

General description

If you are commissioning the creation of an app to an external team, you should mention a few words about yourself first. It’s not about writing the company’s showcase and presenting its whole history, but rather explaining its business objectives, rationale and grounds behind the digital product. A well-defined background will allow the software house to quickly define your company’s needs.

Both Google Play and App Store offer over 5 million apps. Each one wants to satisfy specific needs of the users. Some are targeted at concrete, narrow groups, such as specific occupations, others are a web extension or sales platforms and offer aggregators, while some are independent entertainment products targeted at monetization from microtransactions and/or ads. This is just a few examples of the rich variety of goals that your app might want to meet. PRD (Product Requirements Document) introduction should precisely define the app and answer to the most burning questions regarding its deployment and identify the users’ needs. It is here that you should point out the previously collected information and conclusions from analyses.

Will the app be an extension to the already existing database? Or maybe it has to be written from scratch? What function is the core of the product? How will you monetize it and what business objectives do you want to achieve? Are you planning to expand it in the future? Who is the app targeted at? Example: you are running a large internet store that offers dietary supplements and you would like to create a mobile app dedicated for young, active people. Using the app, you will suggest exercises in line with the target chosen by the user. You will update these exercises according to the current trends. First and foremost, your goal is to facilitate planning cycles for the best results. Your business objective is to have suggestions of your products popping up next to suggestions of exercises and making them available for purchase directly from the app. Even this short description brings about a lot of valuable information for the development team. At this stage, the coders already know what value you want to show your clients and what your business objective is. Moreover, it is obvious that the app will have to communicate with your store on many levels, and you need access to the administrator’s panel to manage exercises and product suggestions. Due to the user’s profile and character of the app, the design should be lively and intuitive.

Technological and product requirements

It is already at the planning stage that you should undertake a series of very important decisions regarding the app’s technological side, and most of all choose the target platforms and operating systems. The app can be tailored to working on computer, tablet or smartphone screens. In every case, the interface layout might be different. A native mobile app dedicated to one system will be more optimized, but transferring it in the future may multiply the required expenses. If you want to release the app for both Android and iOS Apple devices at the same time, a cheaper and more elastic solution is a hybrid. As far as Android is concerned, you should also define the version from which this app will be supported. Moreover, technological requirements should include information about services, servers and databases with which the app will communicate and store data (payment systems, internal accounting system, CRM, social media). Will support with maintenance works be required in the future? Does the company own up-to-date API documentation? Will the app’s operation base upon external software? Should other tools be connected to the app, e.g., for data analysis? If the company staff are to have access to the administrative panel under different scopes of authorization, specify these conditions. All necessary technologies should be indexed, and the next chapter should explain their use.

Description of functionality and app operation scenario

The documents should at the same time point to the key functionality of the app and define the additional functions that it should be supported by. It’s best to lead the coders step by step through the user’s path. It is already at the logging stage that the user can have a few options for that. Does the app connect with the database and enable use of the already existing account to the user? Does it offer the option of logging in using social media? Where will the user’s data be stored? What kind of screen should you view after logging in? What should the interface look like? Each next action or function should be described in all possible scenarios, and the more complex the application, the longer it will take to describe its functionality.

Other elements that should be described in the description of functionality are: cooperation with servers, offline operation (data buffering), the use of social media and geolocation, payment methods, push notifications, layout of the application menu, design, as well as all text content. Of course, not all modules are a must have. Each subsequent one increases the cost and extends the implementation time. In order to examine the interest of the market before they decide on the full version of the program, some companies release a product that only fulfills its basic task (MVP, minimum viable product).  On top of that, the document should point out all the materials that you are able to provide the agency. If you take care of design, content and have technical documentation, this should be mentioned as well, as it can significantly reduce the time required. Alternatively, you can clearly indicate the exact scope of work we expect from mobile app or web developers.

Going back to the example described above: the user can log in using an existing account in the supplement store (and vice versa) and Facebook, after logging in, you should see a human body map with the specified muscles, clicking on the appropriate section takes the user to the list of the most popular exercises and recommended training cycles. For offline operation, the user only has access to previously opened exercises stored in the phone’s memory. Each exercise board should include a suggestion of the product with a description taken from CRM. Push notifications can display reminders about upcoming training and promotions etc. This is, of course, only an example of a very lucid description. The actual specification should be much more elaborate.

Additional information

It is already at the stage of specification where we can include information about the planned budget and deadline. Thanks to this, the software house will be able to assess whether the project is possible to be marketed in this form. Perhaps some of the functions will be too expensive or unnecessary and you will be able to opt out without damaging the app’s functionality. You can list the people involved in the project together with contact details in the additional information. If there was no opportunity for other important observations in the above points, this is the place for all such remarks.

Why is a PRD so important?

An app’s functional specification is the basic element for the agency or freelance developer; it is decisive of acceptance or rejection of a project. On this basis, the software house is able to assess the works required for execution and identify any threats beforehand. The agency can assess whether it has the necessary substantive and technological facilities. Any delay can be costly for both parties. A part of the programming team cannot wait and sit idle for a solution to the problem on the client’s side, and therefore the liquidity of work suffers. It is also possible to verify customer involvement in the project. The specification can also lay the grounds for performing the necessary app performance tests and boundary situations. In turn, as far as the client is concerned, an undoubted benefit is the ability to estimate the budget and time needed for implementation. Thanks to this, the customer can pay “in advance” and not worry about possible underestimation or overestimation of the scale of the project.