There's no shortage of app agencies in London. Search for one and you'll find long directory lists, and nearly every agency on them says it builds award-winning apps. The hard part is comparing the quotes, because they arrive in completely different shapes. One says £18,000 and another says £90,000 for what sounds like the same app.
Day rates explain most of that gap. In the six months to 6 October 2026, the median contract rate in London was £573 a day for Flutter developers, £475 for React Native, £455 for Android and £375 for iOS, according to IT Jobs Watch. A first version built by two developers over 12 weeks comes to about £57,000 in developer time alone at the React Native rate, before design, testing and project management.
I'm Keshav from GIT Infosys. We're one of those agencies, with an office in Wembley and our developers in Jaipur, so read this knowing where I sit. This guide covers what an app really costs in the UK, what pushes the price up, the fees and rules after launch, how to compare agencies, and which questions to ask before you sign.
How Much Does It Cost to Build an App in London?
Short answerBased on current London day rates, a simple first version of an app costs about £25,000 to £32,000, a mid-sized app with payments and an admin panel about £75,000 to £125,000, and a complex app £225,000 or more.
These are our estimates, worked out from the React Native median of £475 a day, with roughly a third added for design, testing and project management. Agencies often quote a higher day rate than a solo contractor because that rate includes those extras. Treat the figures as a sense check for quotes, not a price list.
Median contract day rate in London, 6 months to 6 October 2026
Flutter developer
React Native developer
Android developer
iOS developer
One caution on that chart: the Flutter figure comes from only 9 quoted rates, against 37 for React Native, so it moves a lot from month to month.
| Type of app | Typical example | Build time | Estimated cost in London |
|---|---|---|---|
| Simple first version | A booking, loyalty or reminder app with logins and notifications | 8 to 10 weeks, one developer | £25,000 to £32,000 |
| Mid-sized app | Payments, an admin dashboard and one or two integrations | 3 to 5 months, two developers | £75,000 to £125,000 |
| Complex app | Live tracking, chat, a marketplace or a finance product | 6 to 9 months, three or four developers | £225,000 and up |
Building separate iOS and Android apps roughly doubles the developer days. That's the main reason most first versions are now built once in Flutter or React Native, and the native apps come later, if they're needed at all.
What Pushes the Price Up
The number of screens matters less than people expect. These are the things that really move a quote:
- Two native apps instead of one shared codebase. Separate Swift and Kotlin builds need two sets of developers.
- More than one type of user. A delivery app is really three apps: customer, driver and admin.
- Payments and subscriptions. In-app purchases, refunds and failed payments all need building and testing.
- Anything live. Chat, tracking on a map and instant updates need a proper backend, not just screens.
- Integrations. Connecting to your booking system, ERP or CRM is often where the hidden days are.
- Sensitive data. Health, finance and apps likely to be used by children carry extra legal and security work in the UK.
- A content admin panel. If your team needs to change content without a developer, that's a small web app of its own.
Fees and Rules After Your App Launches
Short answerExpect to pay Apple $99 a year, Google $25 once, and the ICO data protection fee of £52 or £78 a year for most small businesses, plus a share of anything you sell inside the app.
Apple App Store
$99 a year for a developer account, charged in local currency. Apple takes 15% of in-app sales if you earn up to $1 million a year, and 30% above that.
Google Play
A one-off $25 registration. Since 30 June 2026, UK fees for new installs are 20% on one-off purchases and 10% on subscriptions, plus a 5% billing fee if you use Google's billing.
ICO fee
If your app handles personal data, your business usually has to pay the data protection fee: £52 a year for micro businesses, £78 for small and medium ones and £3,763 for large organisations, since 17 February 2025.
The rules around app stores are still moving in the UK. The Competition and Markets Authority gave Apple and Google special status over their mobile platforms in October 2025, and in February 2026 it announced commitments from both on fairer app review and ranking. Commission rates weren't part of that package, and the CMA says its work on them continues.
If children are likely to use your app, the ICO's Children's Code also applies. It covers things like default privacy settings and how much data you collect, and it's far cheaper to design for from the start than to fix afterwards.
How to Compare London App Agencies
Short answerCompare agencies on the same written brief and a quote broken down by feature, not on the headline price or the portfolio slideshow.
- Write a one-page brief. Who uses the app, the three or four jobs it must do, and what "done" looks like for the first version.
- Shortlist three to five agencies. Use referrals, directories like Clutch and GoodFirms, and Google reviews. Then download two apps from each portfolio and use them for ten minutes.
- Send every agency the same brief. Different briefs make the quotes impossible to compare.
- Ask for days per feature. A quote that shows "login: 4 days, payments: 9 days" can be checked. A single lump sum can't.
- Start with a paid discovery stage or a small first milestone. Two to three weeks of working together tells you more than any pitch meeting.
Check reviews on Google, not just on the agency's own website. For what it's worth, ours sits at 4.6 from 170 reviews as of 6 October 2026, and you can read the bad ones as well as the good ones.
Questions to Ask Before You Sign
Ask every agency the same questions, and listen for specific answers rather than reassurance.
Who will actually build it?
In-house staff in London, a team abroad, or freelancers they hire per project.
Listen for names and roles, and a straight answer about where the developers sit.
Whose name are the app store accounts in?
Your Apple and Google developer accounts should belong to your company, not the agency.
The right answer is "yours, and we'll help you set them up."
Who owns the source code?
Get it written into the contract, including what happens if you stop working together.
Listen for full transfer of code and designs on final payment.
What isn't in the price?
Design, testing on real devices, store submission and the first month of bug fixes are often extras.
A good agency lists exclusions without being asked twice.
Native or cross-platform, and why?
Every agency has a favourite. You want the reason that fits your app, not theirs.
Listen for features that need native code, or the admission that yours doesn't.
What happens after launch?
Apple and Google update their systems every year, and apps need fixes to keep working.
Ask for a monthly support price and a response time in writing.
London Agency, Offshore Team or Freelancer?
Short answerA London agency is easiest to work with, an offshore or hybrid team costs less per day, and a freelancer suits small, well-defined jobs. The right pick depends on how much of the project you can manage yourself.
London agency
Face-to-face workshops and the same working hours, at the full London rates above.
Best when the app is central to your business and you want one team to own the result.
Hybrid or offshore
Lower day rates, with the developers 4.5 hours ahead of London in summer and 5.5 in winter.
It works when someone checks in daily and the brief is clear. It's the model we run, with our London office and our app developers in Jaipur.
Freelancer
The cheapest option for a small, clearly defined piece of work.
Risky for a whole app, because if one person gets ill or takes another job, the project stops.
NotePlenty of businesses don't need an app at all to start. If customers mainly want to browse and buy, a fast ecommerce website or a Shopify store works on every phone with nothing to download, and costs a fraction of an app.
From Our Own Work
Reminder Box · an app in our portfolio
Reminder Box is a good example of a narrow first version. It's built for one type of user, the owner of a florist, bakery or gift shop, and it does one main job: it reminds the shop five days before a customer's birthday, anniversary or other occasion, so they can call and take an order.
Signing up takes four steps: register the shop, add customers and their dates, get the reminders, and send the flowers, cake or gift. The app also works offline, which matters in a busy shop with poor signal. I'm not quoting usage figures here, because I haven't checked them myself.
The lesson for a first app holds anywhere, London included: one user, one job, done well. Everything else can wait for version two, once real people are using it.
You can see more of our apps and websites in our portfolio. From the Wembley office we also work with London clients on their websites, including the London International Youth Science Forum.
Common Mistakes When Hiring an App Agency
- Building iOS and Android natively on day one. You pay twice before you know if anyone wants the app.
- Letting the agency open the store accounts. Moving an app between developer accounts later is slow, and Apple has conditions an app must meet before it can move.
- Choosing the lowest quote without a feature list. The cheapest quote is often the one with the most left out.
- Treating launch as the finish line. Apps need updates for new phone software every year. Budget for it from the start.
- Forgetting the privacy work. Both stores ask what data your app collects, and in the UK that has to match what your privacy notice says.
- Planning no marketing. An app with no visitors gets no downloads. Your website, SEO and Google Ads app campaigns are where most first downloads come from.
Your app's icon and store screenshots also do a lot of the selling on the App Store and Google Play. If you need help with app icon and brand design, that's worth planning alongside the build.
Frequently Asked Questions
How much does it cost to build an app in the UK?
Based on London day rates in October 2026, a simple first version costs about £25,000 to £32,000, a mid-sized app £75,000 to £125,000, and a complex app £225,000 or more. Teams outside London or abroad usually cost less per day.
How much do app developers charge per day in London?
Median contract rates in the six months to 6 October 2026 were £573 for Flutter, £475 for React Native, £455 for Android and £375 for iOS developers, according to IT Jobs Watch.
How long does it take to build an app?
A simple first version usually takes 8 to 10 weeks, a mid-sized app 3 to 5 months, and a complex app 6 to 9 months. Store review adds a day or more at the end, longer if the app gets rejected.
Is it cheaper to hire app developers in India?
Yes, day rates are much lower, but you need clear briefs and daily check-ins because India is 4.5 to 5.5 hours ahead of the UK. A hybrid team with a UK office handles meetings in your hours.
What do Apple and Google charge app developers?
Apple charges $99 a year and takes 15% of in-app sales up to $1 million a year. Google charges $25 once, and for new UK installs takes 20% on one-off purchases and 10% on subscriptions, plus a 5% billing fee.
Do I need to pay the ICO fee for my app?
Usually, if your business handles personal data through the app. The fee is £52 a year for micro businesses, £78 for small and medium ones and £3,763 for large organisations.
Should I build a native or cross-platform app?
Most first versions should be cross-platform in Flutter or React Native, which roughly halves the developer days compared with two native apps. Go native when the app depends on heavy graphics or deep device features.
Who owns the code when an agency builds my app?
Only whoever the contract says. Ask for full transfer of the source code and designs on final payment, and keep both store accounts in your company's name from day one.
Sources: IT Jobs Watch, React Native contracts in London; Flutter; Android developer; iOS developer; Apple Developer Program; App Store Small Business Program; Google Play Console registration; Google Play's lower service fees; ICO data protection fee; ICO Children's Code; CMA on Apple and Google commitments. Rates and fees checked 6 October 2026. Cost ranges are our estimates from those day rates. Google rating checked on 6 October 2026.
