Introduction
This is the question we get asked earliest and most often — usually before a founder has even finalised what their product does. It's also a question that gets answered badly a lot of the time, because most advice defaults to "it depends" without actually helping you work out what it depends on.
This guide gives you a proper decision framework, not just a list of pros and cons — plus honest cost and timeline comparisons so you can plan your budget around the right choice.
The Quick Answer
If you need one, here it is: most UK businesses should start with a web app, unless their core function genuinely depends on mobile-only capabilities (camera, GPS, offline use, push notifications as a core feature) or their users are consumers who expect an app-store presence. Read on for why, and for the exceptions that matter.
What's Actually Different Between Them
A web app runs in a browser, on any device, with no download required. Users access it via a URL.
A mobile app is downloaded from the App Store or Google Play and installed on a phone. It can be:
- Native — built specifically for iOS or Android, with full access to device hardware
- Cross-platform — built once (e.g. with React Native or Flutter) and deployed to both iOS and Android
These aren't just different technologies — they come with fundamentally different user behaviour, cost structures, and update processes, which is why the decision matters more than it might first appear.
Decision Framework: Answer These 5 Questions
1. Where will your users actually use this?
- At a desk, for work tasks (admin, reporting, managing data) → web app
- On the go, in short bursts, throughout the day → mobile app
- Both, depending on the user type (e.g. staff at a desk, customers on their phone) → consider a web app for one audience and mobile for the other, sharing a backend
2. Does your core feature require device hardware?
If your product depends on the camera, GPS location tracking, biometric login, offline functionality, or Bluetooth/NFC — you need a native or cross-platform mobile app. Browsers can access some of these (camera, location) with limitations, but not reliably enough for a feature your business depends on.
If your product is primarily about displaying and managing information, a web app can do everything a mobile app can, without the added cost and complexity.
3. How important is app store presence to your customers?
Consumer-facing products in categories like food delivery, fitness, or social apps benefit hugely from being discoverable and visible in the App Store/Play Store — this is a real acquisition channel, not just a technical delivery method. B2B tools and internal business software get little to no benefit from this.
4. What's your update cycle going to look like?
Web apps update instantly — you push a change, and every user has it immediately. Mobile apps go through app store review (which can take 1–3 days, sometimes longer) for every update. If you're in an early, fast-iterating stage — testing features, fixing bugs quickly, responding to user feedback — a web app lets you move significantly faster.
5. What's your budget, and what stage are you at?
Building a mobile app (especially natively for both iOS and Android) roughly doubles your development cost compared to a single web app, unless you use cross-platform tools. If you're pre-revenue or validating an idea, this often makes a web app the financially sensible starting point — you can always build a mobile app once you've proven demand.
Cost Comparison (UK, 2026)
| Version | Web App | Cross-Platform Mobile App | Native Mobile App (iOS + Android) |
| Simple version | £8,000 – £20,000 | £15,000 – £35,000 | £25,000 – £60,000 |
| Mid-complexity | £20,000 – £50,000 | £35,000 – £70,000 | £60,000 – £120,000 |
| Ongoing maintenance | Lower — one codebase | Medium — one codebase, platform quirks | Higher — two separate codebases |
For a full breakdown of mobile-specific costs, see our mobile app development cost guide.
Real Scenarios: What We'd Actually Recommend
A UK startup building a B2B SaaS analytics tool → Web app. Users work at a desk, need instant updates as you iterate, and app store presence adds no value for a B2B admin tool.
A UK startup building an on-demand home services app (e.g. cleaning, repairs) connecting customers with providers → Mobile app for customers (push notifications, location, on-the-go booking matter here), potentially a web app or web dashboard for the service providers/admin side.
A UK restaurant chain building an ordering and loyalty system → Mobile app for customers (push notifications for offers, app-store visibility, camera for loyalty QR codes), web app for restaurant staff managing orders. See our restaurant app development guide for more on this specific case.
A UK professional services firm building a client portal → Web app. Clients check documents and status occasionally, not multiple times a day — a mobile app would be over-engineering for this use case.
The Hybrid Approach: You Don't Always Have to Choose
A significant number of successful products aren't purely one or the other — they use a shared backend with a web app for one part of the business and a mobile app for another (or a web app now, mobile app added later once demand is proven). This is often the most cost-efficient path: the backend, database, and business logic are built once, and each frontend (web, iOS, Android) connects to it.
This is worth discussing with your development partner at the planning stage, not after you've already built one platform — the backend architecture needs to be designed to support this from the start if it's part of your roadmap. Our web application development team plans this kind of shared-backend architecture as standard practice for clients who expect to expand to mobile later.
Signs You're Making the Wrong Choice
- You're building a mobile app mainly because "that's what apps are" — without a specific feature that actually requires it
- You're building a web app for a product where your competitors' entire acquisition strategy runs through app store search and rankings
- You're building both platforms simultaneously before validating either one with real users
- You haven't asked your actual target users which they'd prefer or already use
Still Deciding?
The right choice depends on specifics of your product and users that a general guide can't fully account for. If you'd like to talk through your specific situation, get in touch for a free consultation, or explore our web application development and mobile app development services to see how we approach each.
