I run an app development company. Hardly a day goes by without someone telling me they’ve had “a good idea for an app” – usually just before asking me to develop it for them.

The problem is, very few apps are about a single ‘good idea’. As Rob Corradi puts it:

Ribrob on Twitter: Apps are the new novel, everyone has an idea for one, but most people don’t do anything about it…

He’s right. However, I’d go a step further:

Daveaddey on Twitter: @Ribrob Except most would-be authors don’t ask us to write their novel for them.

So what makes for a good app?

A good app

I’ve talked in the past about the types of apps that suit mobile devices, and the kinds of ideas that may seem good, but aren’t commercially viable. You should always assess the viability of an idea before starting an app project, to weed out ideas that aren’t going to be profitable, no matter how much you might wish otherwise. However, this filtering process doesn’t mean that the ideas that do pass the test will turn into successful apps – it just helps to get rid of the ideas that definitely won’t.

There are many things that can make for a successful app:

Unique technology (Shazam, Word Lens)
Exclusivity of content (Rightmove, IMDb)
Timely access to an existing service (Facebook, Twitter)
Innovative concept (Sleep Cycle, Talking Carl)
Great game design (Angry Birds, Plants vs Zombies)
Beautiful interactivity (Three Little Pigs, The Waste Land)
Excellent UI design (Reeder, Flipboard)
All of these apps could be considered a ‘good idea’, in that they are fun or useful to have on a mobile device. However, they aren’t apps where the idea itself is the reason the app is a success.

It’s useful to separate these apps into three distinct types:

Those based on good subjects
Unique technology
Exclusivity of content
Timely access to an existing service
Those based on good concepts
Innovative concept
Those based on good implementation
Great game design
Beautiful interactivity
Excellent UI design
These three types are important when deciding if you have a potentially successful app. Let’s take a look at each in more detail.

A good subject

It’s important to separate out good ideas for apps from good subjects for apps. If your idea is to make an app based on somebody else’s data, then you don’t have a good idea for an app – you’ve just identified a good subject.

Many of the ‘good ideas’ I hear – including the ones where people ask me to sign an NDA – fall into this category. Most are doomed from the off, because the person with the idea doesn’t own the rights to the subject. Occasionally this can lead to a creative partnership with the subject’s owner, but usually the owner is already aware of how useful their content could be on a mobile device, and isn’t looking to sign over a portion of their app revenue to someone else who’s spotted this fact.

A good concept

There are surprisingly few apps where a single idea – or rather, an innovative concept – is the thing that makes them great. Here are three:

Sleep Cycle. The principle behind this app – using the accelerometer to wake you up when you are most likely to feel refreshed – is a great piece of lateral thinking.
Talking Carl. The genius idea here is that the on-screen character repeats a child’s words in a funny voice – resulting in a feedback loop of laughter and repeated laughter that can keep a child entertained for hours.
Air Display. This turns an iPad into an additional screen for a Mac. Given that many people own and carry both devices, it’s a neat way to make the devices better than the sum of their parts.
The trouble with good concepts is that most of them have already been thought of. It’s also easy for more than one person to have the same idea, and to spend months developing similar products in isolation. Having an innovative concept is (in itself) a risky strategy for success.

A good implementation

No matter how good your concept or how appropriate your subject, your app still needs to be well implemented. As John Gruber put it in 2008:

Figure out the absolute least you need to do to implement the idea, do just that, and then polish the hell out of the experience.

He’s right. To prove it, here are the concepts behind some of the top-selling apps of all time. If someone pitched these to you on concept alone, would you invest in them?

A game where you throw birds at pigs
A book about the periodic table
A game where you tap along to music
You’ll probably recognise Angry Birds, The Elements and Tap Tap Revenge. The success of these apps doesn’t come from a single idea – it comes from months of design and development spent creating a polished and engaging end product. This requires skill, experience and patience from a wide range of complementary disciplines. It’s expensive, and it doesn’t always lead to a successful product, however good the original idea might be.

Good ideas

In fact, developing a great app is about having lots and lots of good ideas, all the way throughout development. The killer idea that makes a good app great often happens a couple of weeks before launch – and only because there’s a foundation of great ideas already in place.

Here’s an example. We created an app for British publisher Faber and Faber, as a tie-in for their Missing DoSAC Files book. The print version of the book is a dossier of top secret documents left on a train by Malcolm Tucker, the lead character from BBC political satire The Thick Of It.

The app incarnation of the book began with a brilliantly simple idea, suggested by developer Henry Cooke. His idea was this: what if Malcolm had lost his iPhone – and you found it? (This is a good idea in itself, and led to a very nice app title – Malcolm Tucker: The Missing Phone.)

What made this very good idea into a really good app was the ongoing ideas generation and refinement from the entire team involved in the app’s development. The project only succeeded because of Henry’s continued creative development, Rob Corradi’s design input, my production role, Alyson Fielding’s story consultancy, a willing publisher in Henry Volans, and the direct involvement of series creator Armando Iannucci and his writing team. Malcolm Tucker became the first app to be nominated for a BAFTA; this wouldn’t have happened if even one of these people hadn’t been involved.

Crucially, the project had a killer idea with three weeks to go until launch. Henry’s storytelling engine had enabled Alyson to test and refine the app’s storyline, but after extensive testing, the story wasn’t proving satisfying enough. Alyson’s idea – to expand the story to include emails as well as voicemails – could only have come at this point in this project, and made all the difference. It was a small idea, but a crucial one.

I’ve singled out Henry and Alyson for two particular moments of inspiration. One of the nicest things about this project was that it was often hard to say exactly who had a particular idea, because the ideas came from creative discussions when solving particular problems. This collaborative approach is so often the reason behind an app’s success.

So will you develop my idea into an app?

If you own the rights to a great subject for an app, then you’re in a good starting position. Craft (and graft) will be needed to convert your subject matter into a great app, but you’re bringing something of value. Don’t expect a developer to take on all of the financial risk – but if your subject matter is juicy enough, they may agree a revenue-share to bring it to market.

If you’ve come up with a good concept for an app, don’t expect a developer to get too excited, or to sign an NDA. Developers don’t struggle to come up with ideas for apps – their main problem is deciding which ideas to devote their time and energy to. That’s not to say your concept isn’t a good one, but your challenge will be in convincing a developer to choose your concept as the one they implement. This almost certainly means you’ll need to take on some of the financial risk for the project.

As for good implementation – well, that’s what developers do best. If you trust a good developer to do a good job, you’ll be well on the way to creating a great app.