Short answer: web app development in the UK in 2026 costs about £15,000 to £35,000 for a focused first version, £35,000 to £100,000 for a full application with accounts, a custom backend and integrations, and £100,000 and up for platforms with payments, real-time features or heavy scale. A web app is cheaper than a native mobile app for the same scope because there is one codebase and no app-store cycle. Below are the ranges, what moves them, and a worked example.
Web app, website, or mobile app?
A website presents information and captures enquiries. A web app is software that runs in the browser: users log in, data changes, things happen. A mobile app is installed from a store. Many businesses that ask for an app need a web app, because it runs on every device, updates instantly, and does not need store approval. If you need push notifications, offline use or the camera as a core feature, read our mobile app development cost guide; if you need a marketing site, the website cost guide.
Web app development cost by scope (UK, 2026)
| Scope | What it includes | Typical UK cost | Timeline |
|---|---|---|---|
| Focused first version | One core workflow, login, a few screens, one integration | £15,000 to £35,000 | 8 to 12 weeks |
| Full application | Multiple user roles, custom backend, dashboards, several integrations, admin | £35,000 to £100,000 | 3 to 6 months |
| Platform | Multi-tenant, payments, real-time collaboration, high availability, compliance | £100,000 to £300,000+ | 6 to 12 months |
| Legacy modernisation | Re-platforming an existing app in phases | £30,000 to £150,000 | 3 to 9 months |
These are industry-typical UK ranges. Day rates for a UK agency team run £400 to £900; a focused first version is roughly 30 to 60 team days across design, development, testing and management.
What drives the cost
- Roles and permissions. Each user type multiplies screens and test cases.
- Backend complexity. A UI over an existing API is cheap; custom business logic, reporting and background jobs are not.
- Integrations. Payments, accounting, CRM, maps, messaging, and any legacy system. Budget £1,000 to £5,000 each.
- Real-time features. Live updates, chat, collaborative editing and notifications add infrastructure and testing.
- Design depth. A component-library interface is quick; a custom, animated product experience is a design project in its own right.
- Data and migration. Importing and cleaning existing data, and running two systems in parallel during a switch.
- Compliance and security. Payment data, health data, or large volumes of personal data bring audits and extra engineering.
The stack question
Most modern UK web apps are built on React or Next.js with a Node, Python or Go backend and a managed Postgres database, hosted on AWS, Azure or a platform like Vercel. The stack rarely changes the price much; what changes it is whether the team has built this kind of app before. Ask for two examples of comparable apps and how long each took.
A worked example: a customer portal for a service business
The brief: customers log in, see their jobs and quotes, approve a quote, pay a deposit, and message the office; staff see the same from the other side; the owner sees a dashboard. Two roles, around ten screens, Stripe for payments, one accounting integration, email notifications. That is a full-application build at roughly £40,000 to £60,000 over four to five months. Without payments and messaging, and with the portal reading from a configured CRM instead of its own backend, it drops to £15,000 to £25,000 and ten weeks, which is where most first versions should start.
Ongoing costs
| Item | Typical cost |
|---|---|
| Hosting and database | £50 to £500 a month |
| Third-party services (payments, email, SMS, maps) | Usage-based; payments around 1.5 to 2.9 percent plus a fee |
| Monitoring and error tracking | £0 to £100 a month |
| Maintenance and small changes | 15 to 20 percent of the build cost per year |
| Retained development | £8,000 to £30,000 a month for a live product with a roadmap |
How to keep the cost down
- Scope the first version to one workflow that changes how you work, and ship it.
- Use managed services for auth, payments, email and file storage.
- Pay for a short discovery so the estimate is a scope, not a guess.
- Insist on two-week sprints with a demo, and on owning the code from day one.
Cost by type of web app (UK, 2026)
| Type of web app | Typical UK cost | Timeline | What drives it |
|---|---|---|---|
| Customer portal | £20,000 to £60,000 | 10 to 20 weeks | Documents, payments, messaging, notifications |
| Booking or scheduling system | £25,000 to £70,000 | 10 to 20 weeks | Calendars, availability rules, reminders, staff views |
| Internal operations tool | £15,000 to £45,000 | 8 to 14 weeks | Roles, forms, workflow states, reporting |
| Dashboard or reporting app | £15,000 to £50,000 | 8 to 14 weeks | Data sources, charts, permissions, exports |
| Marketplace (two-sided) | £60,000 to £200,000 | 4 to 9 months | Two user types, payments and payouts, trust and disputes |
| SaaS product, first version | £40,000 to £120,000 | 3 to 6 months | Multi-tenancy, billing, onboarding, admin |
| Progressive web app for field staff | £25,000 to £70,000 | 10 to 20 weeks | Offline mode, camera, location, sync |
A sample budget breakdown
For a £45,000 customer portal, a typical UK agency budget looks like this:
| Phase | Amount | What it buys |
|---|---|---|
| Discovery and scoping | £3,500 | User flows, data model, integration plan, fixed price |
| Design | £6,500 | Wireframes, interface, component library, responsive rules |
| Backend development | £12,000 | Database, API, authentication, business logic, integrations |
| Frontend development | £11,000 | Screens, forms, dashboards, states |
| Testing and QA | £5,500 | Automated tests, cross-browser and device testing, security review |
| Project management | £4,000 | Sprints, demos, communication |
| Deployment and handover | £2,500 | Hosting, monitoring, documentation, training |
Web app vs no-code
No-code and low-code tools (Bubble, Softr, Glide, Retool for internal tools) can build a first version for £2,000 to £15,000 and are the right call when the workflow is standard, the user count is small, and speed matters more than ownership. They stop being the right call when you need custom logic the tool cannot express, when monthly fees scale with users, when performance or data residency matter, or when the app is the product you sell and investors will ask who owns it. Many businesses start on no-code, prove the workflow, and commission a custom build once the limits show; that is a reasonable path as long as the data can be exported.
What affects the timeline more than the cost
- Decisions. A product owner who answers within a day keeps a sprint on track; one who answers weekly doubles the calendar without changing the budget much.
- Content and data. Screens are built quickly; the real data to fill them arrives slowly. Start the data work in week one.
- Third-party approvals. Payment providers, banking connections and some APIs have their own review cycles.
- Testing on real devices. Reserve time for the phones and browsers your users actually have, not the ones the team has.
Questions to ask a web app agency
- Which two comparable apps have you built, and how long did each take from kick-off to live?
- What is in the price, what is excluded, and what would change the price?
- Who owns the code, the hosting accounts and the documentation?
- How do you handle security, backups and monitoring after launch?
- What does a change cost after launch, and how quickly can it ship?
Hosting and running costs by scenario
Running costs are small next to the build but they never stop, and they scale with success. A customer portal for a service business with a few hundred users typically runs £50 to £150 a month: a managed database, a hosting platform, email sending, error tracking and backups. A booking system with a few thousand users and SMS reminders runs £150 to £500 a month, most of it messaging. A marketplace or SaaS product with tens of thousands of users runs £500 to £5,000 a month, with the database and background processing as the largest items, plus payment fees on every transaction. Two rules keep this under control: use managed services rather than servers you patch yourself, and put cost alerts on every account in week one so a bug that loops or a traffic spike shows up as an email rather than an invoice.
Security and compliance basics every web app needs
Whatever the scope, a UK web app that holds customer data needs authentication with strong password rules or single sign-on, encrypted connections and storage, role-based access so users only see what they should, audit logs for anything financial or medical, regular dependency updates, backups that have been tested by restoring them, and a privacy notice that matches what the app actually does. Payment data should never touch your servers; use a provider that handles it. Budget a security review before launch and an annual check after; the cost is a few days, and the alternative is a breach notification.
Bottom line
A UK web app costs from around £15,000 for a focused tool to six figures for a platform. The spread is scope, and it is decided before the build. Our web application development service covers the whole lifecycle; the custom software cost guide covers the wider picture.
Book a free call and we will scope your app and give you a real range before you commit to anything.