How to Write an App Specification + FREE Template Download


10 minute read
Alumni: Charlie Harman

Alumni: Charlie Harman

Marketing Manager

Digital Insights

As an app developer, we’re contacted on a daily basis by people with great ideas, looking for help to develop experiences or asking for quotes for their app. Here’s the problem: it’s impossible to give prices off the bat.

The potential scope of an app build is vast and varied. Is it a simple catalogue, or does it use location-based AR to deliver full audio performances depending on the user’s movements? In between those two extremes, there are multitudes of features, functions and factors, which can all affect the price.

For those thinking ‘what a cop out!’ we will say this: an app is like a work of art. If you want a copy of an established hit, you can look into lower cost ways to get it reproduced. If you want an original, you need to invest. You might get a near-copycat app for £6,000, but if you want something new, tailored and truly original, the cost will be considerably more.

To give you a ballpark, what we really need is a brief: a plan of work that gives us a feel for the size of the undertaking, and our role within it. Are we developing an all-encompassing experience from scratch, or simply providing the technical nouse?

App specifications work in two ways. First, they allow us to get a real feel for your needs, and help us ascertain the size and price of the job. Second, they give you focus for the project.

We’ll run through the important elements of an effective brief, then give you a download to get your thoughts down on paper and over to us.


It’s useful to know the basics about the business or organisation, your role within it, and the big idea behind the app. In particular, let us know if this is your first foray into app development, or if you’re already savvy.

Unique selling point

When you have a brilliant idea for a never-before-seen mobile app… Google it. Look around for someone who’s had the same idea. Someone probably has. There are millions of apps in the world, so check out your competition. See who’s doing something similar, and work out what makes your idea different.

While we’re talking about this – you may be feeling protective of your idea, and want us to sign a non-disclosure agreement. As a rule, we try not to do this. They’re restrictive documents which our lawyers have to look over, meaning it’s a week before we can even have a conversation with you. They hinder progress, and they’re unnecessary. We’ve been respecting our partners’ confidentiality since we began. If we didn’t do that, we’d lose business – word would get out and clients would go elsewhere. We would have nothing to gain and a lot to lose by disclosing your idea, so we won’t do it.


Who is your app for? Knowing your intended users will inform many of the decisions we’ll make together. It’ll help us design an appropriate user experience – something that’s accessible, intuitive, and visually appropriate for your target market.

To help with this stage of the brief, try to create a customer persona or two. How old are your target users? How familiar are they with technology? What do they read, watch, enjoy and do? The more you know about them, the more we can tailor the app to them. All your market research for the project should inform this step of the brief.


What do you want the app to do for your business or brand? This has nothing to do with how the app works (that’s the next bit). It’s about your reasons for having an app in the first place, the problem that your app is going to solve. Look at your current metrics and think about what improvements you’d like to see, what benchmarks you have to meet for your app to be a success. Telling us this helps you consolidate your idea and understand how you’ll measure its success – what are your goals in terms of app ROI?


What do you want the app to do? This question needs a simple, one-sentence answer. Imagine the app is built, you’re ready to upload it to the app store or send it out to your personnel. What would you tell them to explain why they need it?

This is a good time to think about comparative research again. Sometimes it’s easier to describe your app in terms of “bits” of other apps or physical activities that inspired it. Does your app have any real-world or digital inspirations? If so, tell us about those too.


Most app developers will ask whether you want your app developed for iOS, Android, Windows or all of the above. This is where your audience research comes in. Native development for more than one platform has the potential to double your costs, so why splash out on Android if your target audience all have iPhones? This isn’t an issue for us as we made the decision to develop in React Native, which is a cross-platform language.

It’s also useful to think about why your project needs to be an app. Apps aren’t always the answer: depending on the project, it’s possible a responsive website could do the job just as well. Read more on that here…


We know you’re looking for a competitive quote, so you might not want to give away what you’re willing to pay – but giving us a ballpark figure ultimately yields better results for you.

Having that figure helps developers estimate what’s feasible for your build, understand the constraints you’re working under, and prioritise features. If something would be too expensive, we can suggest a realistic alternative. Without a rough idea of your budget, we have to guess – which means you may get ideas that aren’t as ambitious as you’d like, or costs beyond your means.

What we can tell you is that app development usually starts at £10,000, with many apps costing between £40-100k. However, mission critical apps like the Ubers and Snapchats of the world could easily push £500k.


If you’re working to a deadline, or with partners who have one, or if there’s an event you want to be built into the process of development and launching – let us know. Try to give us as detailed a breakdown of time constraints as you can.

Features and functionality

Now it’s time to dig into the vitals of the app – the specific options you want to make available for users, rather than the one-sentence description. It may be that you don’t have too many specifics in mind, and want your development partner to define the user experience – which can help you get a different perspective. Unless you’re a UX designer, it’s best to leave most of the work in defining the actual UI, wireframes and experience to your agency.

If you’re having trouble establishing this, work through all the things you can do with a smartphone – take pictures, make calls, get directions, use the compass, play audio and video and so on. How could those capabilities be used in your app?

Once you’ve done that, think about what your app needs to do, and what it’d be nice if your app did. Here are some of the most popular features people request:

  • Push notifications – will the app send out reminders?
  • Geolocation – will the app show users where they are or where to go?
  • Social integration – will the app share to Facebook, Twitter, Instagram…
  • Logins – will the app have personal profiles?
  • Money model – will people pay for the app when installing, or will there be in-app purchases?
  • User-generated content – will users give ratings or reviews, or upload stories and scores?
  • Linking – will users be guided toward an integrated website, or a YouTube channel?

Finally: where does the information come from? Does the app draw on an external database (e.g. calorie trackers, news apps). If so, your developer needs to know if that database needs building or already exists. If it already exists, they need to know if there’s a web server and documentation for an Application Programming Interface (API). The more information you can provide, the easier the design process will be – but the main thing is to know what data your app will use and where it’ll be stored.

Graphic Design

This stage of the build will be a collaboration between designers and developers. Most app development agencies will have in-house graphic designers who are well practised at designing for mobile.

If you want to work with your own graphic designers, they’ll need to collaborate with your development agency. There will be questions about varying screen dimensions, nuances in behaviour and functionality that need to be resolved – and this may require more time from your designers than you expect, even after the graphic design stage is formally completed. It also means your developers will need to commit time to managing these questions.

In any case, the designers will need their own specification to work from, and any firm direction you can give them will be helpful. Do you know what colours and fonts you want? If you have brand guidelines, like a style guide, send those too.

Maintenance plan

You can discuss this with your developers down the line, but it’s good to show that you understand that apps do need maintenance, and you’ve thought about how this will work. What changes may need to be made over time?

Extra info

Finally, try to provide a call sheet with all the contact details and short bios of everyone involved in the project at your end. Include email addresses, roles and responsibilities. If there’s anyone we might need to talk to, let us know who they are – it’s better for us to have too much information than not enough.

That’s it. You’re ready to start writing your spec. We’ve created a handy PDF template for you to use. Download it here and get started – you’ll have a brief for us in no time.

Download App Specification Template

Get your Free App Specification Template


(Don’t forget it’s important to be flexible too. Think of this specification as an aid document. Your chosen developers should apply their expertise and experience to ensure your app is the best it can be, which might mean many things about your app will change in those early days. Your chosen agency should inform you and help guide you through those decisions.)


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