App development company in London
Mobile app development for London businesses: iOS, Android and web apps, from first brief to App Store and Google Play release, built by one dedicated team.
- Custom quote after a brief
- No sales pitch
Company-wide:★★★★★ 4.9+ on Clutch·250+ brands·10 offices
UnFoldMart is an app development company with an office at 32 London Bridge St, London SE1 9SG. We design and build iOS, Android, cross-platform (Flutter, React Native) and web apps for London businesses, from discovery to store release and support, with one small dedicated team led from our international offices. Meetings with London clients are by video in English, and pricing is a custom quote after a short brief and a free 30-minute call.
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Key facts
| Service | Mobile and web app development: iOS, Android, cross-platform (Flutter, React Native), web apps and PWAs, backend and store release |
|---|---|
| Company | UnFoldMart |
| Office | 32 London Bridge St, SE1 9SG London, United Kingdom |
| Meetings | By video (in-person meetings only at our Frankfurt and Zürich offices) |
| Languages | First call in English; project calls by video in English |
| Time zone | UK time (GMT/BST); project teams are led from our international offices |
| Typical timeline | Discovery 1–3 weeks · design 2–5 weeks · first version 8–16 weeks · testing and store release 1–3 weeks (ranges, not guarantees) |
| Pricing | Custom quote after a short brief: fixed-scope project or ongoing product team. No price list. |
| Booking | Free 30-minute video call ↗ |
| Company-wide | 10 offices in 10 markets · 250+ brands · 500+ projects · 4.9+ on Clutch · 8 working languages |
Mobile app development for London businesses
London is one of the world's largest financial and technology centres, with fintech, media, retail and professional services competing for attention on the same phones. Users expect fast, polished apps, and regulated sectors expect careful data handling.
London at a glance
- IndustriesFintech, retail, media, property, health, SaaS
- Data lawUK GDPR and the Data Protection Act 2018
- PaymentsCards, Apple Pay, Google Pay, pay by bank
- LanguageEnglish
- Time zoneGMT in winter, BST in summer
Fintech and financial services
Onboarding, account and payment apps with security reviews built in.
Retail and consumer brands
Shopping, loyalty and booking apps.
Professional services and B2B
Client portals and internal tools.
What our London app developers build
iOS and Android app developers, Flutter and React Native developers, web app development and the backend behind it.
iOS and Android apps
Swift and Kotlin, full device access.
Cross-platform apps
One React Native or Flutter codebase.
Web apps and PWAs
Portals and tools, no store needed.
Backend, APIs and integrations
Accounts, payments, CRM, ERP.
MVPs and first versions
Test your idea with real users.
Takeover and support
Review, fixes, upgrades, rebuilds.
Native, cross-platform or web app?
Native iOS app development in Swift, Android in Kotlin, or one Flutter or React Native codebase. We recommend one in discovery.
| Native | Cross-platform | Web app / PWA | |
|---|---|---|---|
| Code | Swift (iOS) and Kotlin (Android) | One codebase: Flutter or React Native | One codebase: TypeScript, React |
| Performance and device features | Best; full device access | Very good for most apps | Good; limited device access |
| Time to both stores | Longest: two apps | Usually faster | No store needed |
| Best for | Demanding, device-heavy apps | Most business and consumer apps | Portals and internal tools |
Apps we can build
Common app types; illustrative screens, not client work.
Booking and scheduling
Pick a slot, pay, get reminders.
Shop and loyalty app
Browse, buy, collect points.
Customer portal
Orders and documents, one login.
Field-service tool
Jobs and checklists on site.
Marketplace
Two sides meet and book.
Finance dashboard
Balances and reports at a glance.
- Chat assistant
- Smart search
- Document reading
- Recommendations
How we work
From brief to store release, with a working build at every stage.
- 1BriefScope and quote
- 2PrototypeClickable design
- 3SprintsDemo every two weeks
- 4Store releaseApp Store · Google Play
Timeline
| Phase | Typical duration | You get |
|---|---|---|
| Discovery and scope | 1 to 3 weeks | Written scope and quote |
| UX and UI design | 2 to 5 weeks | Clickable prototype |
| Build in sprints | 8 to 16 weeks for a first version | Test build every sprint |
| Testing and store release | 1 to 3 weeks | Real-device and security testing, store submission |
| Support and next versions | Ongoing, as agreed | Monitoring, updates, next versions |
Typical ranges in weeks, not a guarantee.
How to choose an app development company in London
Six checks before you sign, whoever you hire.
Platform fit
Ask which approach they recommend (native, Flutter, React Native or web) and why.
UnFoldMart: We recommend one in discovery.
A written scope and quote
What is in, what is out, and how changes are priced.
UnFoldMart: Scope, timeline and price in writing.
A visible process
A clickable prototype first, then demos and test builds you can install.
UnFoldMart: A demo after every two-week sprint.
Security and data protection
How data is protected and tested before release.
UnFoldMart: OWASP MASVS, security testing before launch.
Store release and ownership
Who submits to the App Store and Google Play, and who holds the accounts and code.
UnFoldMart: App Store and Google Play submission is part of our release step.
Support after launch
Updates for new iOS and Android versions, monitoring and a clean handover option.
UnFoldMart: Support agreed in your quote.
Agency, freelancer or in-house team?
| App agency | Freelancer | In-house team | |
|---|---|---|---|
| Skills | Design, build, testing and release in one team | Usually one specialism | The roles you hire |
| Start | After scope and quote | Often quick | After hiring |
| Continuity | Team covers absences and handover | Depends on one person | High while the team stays |
| Your management effort | Low to medium | Medium to high | High |
| Cost model | Project quote or monthly team | Hourly or daily rate | Salaries, hiring and tools |
| Best for | A full app, start to finish | A defined, smaller task | A long-term core product |
What affects the cost
No price list. Your quote depends on these factors.
- PlatformsiOS, Android, web.
- Screens and featuresHow many, how complex.
- IntegrationsPayments, CRM, ERP.
- Design depthStandard or custom.
- TimelineYour launch date.
- Regulated featuresIdentity checks, payments and FCA-regulated flows need extra review time.
Ways to work with us
Fixed-scope project
Scope and price in writing.
Ongoing product team
A dedicated team, monthly.
Discovery first
A scope you can use anywhere.
How quoting works
- Short briefWhat and for whom.
- Free 30-minute callBy video, in English.
- Written estimateScope, timeline, price.
- You decideNo obligation.
UK GDPR and data protection
This is general information, not legal advice. Your legal adviser has the final word.
UK GDPR and the Data Protection Act 2018
Set the rules for personal data in the UK. We plan lawful basis, consent, data minimisation and deletion into the app from the first sprint.
Official source: Data Protection Act 2018 (legislation.gov.uk) ↗PECR
The Privacy and Electronic Communications Regulations cover cookies and similar storage on devices, and electronic marketing such as marketing emails and texts.
Official source: PECR (legislation.gov.uk) ↗ICO guidance
The Information Commissioner's Office is the UK regulator for data protection and publishes guidance for organisations.
Official source: ico.org.uk ↗Public standards we align our work to
Working with us from London
One dedicated team; projects are led by UnFoldMart from our international offices.
Our London office
32 London Bridge St, SE1 9SG London
By video
Workshops, demos and weekly check-ins by video.
Language
Calls and project work in English.
Time zone: UK time (GMT/BST)
Office-hours overlap: –
09:00–18:00 local time in both offices.
Company-wide figures across all our services, not app projects.
- Zürich · in person
- Frankfurt · in person
- London
- Amsterdam
- Paris
- Madrid
- Warsaw
- Singapore
- Vancouver
- Gurugram
Frequently asked questions
App development in London: before you book a call.
Do you have an office in London?
Yes. UnFoldMart's London office is at 32 London Bridge St, London SE1 9SG. Workshops, design reviews and weekly check-ins with London clients take place by video, in English.
How much does it cost to build an app in London?
Pricing is custom. Cost depends on platforms, screens and features, integrations, design depth, compliance needs and your timeline. After a short brief and a free 30-minute call, you get a written estimate.
How long does it take to build an app?
Typically: discovery 1 to 3 weeks, design 2 to 5 weeks, build 8 to 16 weeks for a first version, testing and store release 1 to 3 weeks. These are ranges, not guarantees.
Should we build a native app or use Flutter or React Native?
Native (Swift for iOS, Kotlin for Android) suits top performance and deep device features. Cross-platform (Flutter or React Native) shares one codebase and usually reaches both stores faster. We recommend one in discovery.
Do you build apps for fintechs in London?
Yes, we build customer and internal apps for financial companies. Security testing runs before every release, and we document how the app handles data and access so your compliance team can review it.
How do you handle UK GDPR and the Data Protection Act 2018?
We plan lawful basis, consent, data minimisation and deletion into the app from the first sprint, and collect only the data the app needs. Your legal adviser has the final word.
Can you connect the payment methods UK users expect?
Yes. UK users expect cards, Apple Pay and Google Pay, and pay by bank is growing. We connect the methods your payment provider supports.
Who works on our project, and how do we communicate?
Projects are led by UnFoldMart from our international offices, with a small dedicated team. Calls are by video, in English, with a demo after each sprint.
Can you take over an existing app?
Yes. We start with a review of the code, the store listings and the backend, then fix, upgrade or rebuild in steps, so your app stays available.
Can you add AI features to our app?
Yes, for example a chat assistant, smart search, document reading or recommendations, built in with your data under control. See our AI agent development service for more.
Building an app in London?
Tell us what you want to build; the quote follows in writing.