What Is a Web App? A Beginner's Guide
If you have ever wondered what a web app actually is and whether your business needs one, you are in the right place. This guide explains what web apps are, how they work, and why thousands of UK businesses rely on them every day.
A Simple Definition
A web app (short for web application) is software that runs in your web browser. Unlike traditional desktop software that you install on your computer, or mobile apps that you download from an app store, a web app lives on a remote server and you access it through a URL — just like visiting a website.
The key difference between a web app and a standard website is interactivity. A website mostly presents information for you to read. A web app lets you do things: log in, enter data, manage records, process orders, generate reports, communicate with others, or automate tasks. Think of it as a tool rather than a brochure.
If you have ever used Gmail, Trello, Xero, or Google Docs, you have already used a web app. These are all pieces of software that you access entirely through your browser without installing anything.
How Web Apps Work
The basics behind the browser
Web apps follow a straightforward pattern. When you open a web app in your browser, here is what happens behind the scenes:
1. The Front End (What You See)
Your browser loads the user interface — buttons, forms, menus, dashboards. This is built with HTML, CSS and JavaScript, the same technologies used for websites. Modern frameworks like React or Vue.js make these interfaces feel fast and responsive, almost like a native desktop application.
2. The Back End (The Engine Room)
When you click a button or submit a form, your browser sends a request to a server. The server runs the application logic — processing your data, checking permissions, running calculations, or talking to other services. This is built with languages like Node.js, Python or PHP.
3. The Database (Where Data Lives)
Most web apps store information in a database. Customer records, order history, user preferences, uploaded files — all of this data is securely stored and retrieved when needed. This is what makes a web app genuinely useful: it remembers things and works with real information.
All three layers work together seamlessly. As a user, you simply open your browser, go to the web app's address, and start working. There is nothing to install, no updates to manage, and you can access it from any device with an internet connection.
Web App vs Website vs Mobile App
Understanding the differences
These three terms get used interchangeably, but they mean quite different things. Here is a clear breakdown:
| Feature | Website | Web App | Mobile App |
|---|---|---|---|
| Primary purpose | Inform and present | Perform tasks and process data | Perform tasks on mobile devices |
| Interactivity | Low (read content, fill forms) | High (CRUD operations, workflows) | High (device-native features) |
| Access method | Browser via URL | Browser via URL | Download from app store |
| Installation needed | No | No | Yes |
| Works across devices | Yes | Yes | Platform-specific (iOS/Android) |
| Development cost | Lower | Medium to high | High (often need two versions) |
For a deeper comparison, read our article on web apps versus websites which covers the topic in more detail. Many UK businesses find that a web app gives them the best of both worlds — accessible on any device, no downloads required, and as powerful as traditional software.
Common Examples of Web Apps
You probably use several already
Web apps are everywhere. Here are some you likely recognise:
Productivity and Communication
Gmail, Google Workspace, Microsoft 365 Online, Slack, Notion and Trello are all web apps. They let teams collaborate, manage projects and communicate without installing desktop software.
Business and Finance
Xero, QuickBooks Online, Stripe Dashboard, HubSpot and Salesforce all run in the browser. They handle accounting, payments, CRM and sales pipelines — critical business functions accessed through a simple URL.
Custom Business Tools
Many UK businesses build their own web apps: staff rostering systems, client portals, quoting tools, inventory managers, booking platforms and internal dashboards. These are tailored to specific workflows that off-the-shelf software cannot handle. See our guide to examples of business web applications for more real-world use cases.
Why UK Businesses Use Web Apps
The practical benefits
Accessible From Anywhere
Your team can use the app from the office, from home, or on the go. All they need is a browser and an internet connection. This has become essential for modern businesses with remote or hybrid teams.
No Installation or Updates
Because the app runs on a server, updates are deployed once and everyone sees them instantly. No more chasing employees to update their software or dealing with version conflicts.
Automate Manual Processes
Spreadsheets and email chains break down as businesses grow. A web app can automate approvals, notifications, calculations and reporting — saving hours of admin every week.
Centralise Your Data
Instead of information living in scattered spreadsheets, email inboxes and paper files, a web app brings everything into one place. This gives you a single source of truth and makes reporting straightforward.
Scale as You Grow
A well-built web app grows with your business. Adding new features, supporting more users, or integrating with other tools is far easier than trying to stretch spreadsheets or off-the-shelf software beyond their limits.
If you are exploring whether a web app is right for your business, our custom web app development hub covers everything from planning to launch. You can also learn about our web application development services to see how we help UK businesses build exactly what they need.
Frequently Asked Questions
No. Web apps run entirely in your browser. You access them through a URL just like a website, so there is nothing to install or update on your device. Some web apps can be added to your home screen as a Progressive Web App (PWA), but even then no app store download is required.
Some can. Progressive Web Apps use service workers to cache data locally, allowing limited offline functionality. However, most web apps require an internet connection because they communicate with a server to store and retrieve data. Your developer can advise on whether offline capability makes sense for your use case.
Costs vary widely depending on complexity. A simple internal tool might start from around £3,000 to £8,000, while a full customer-facing platform with user accounts, payments and integrations could range from £10,000 to £50,000 or more. The best approach is to start with a Minimum Viable Product to validate your idea before committing to a larger build.
Thinking About Building a Web App?
We help UK businesses turn ideas into working web applications. Whether you need a simple internal tool or a full customer-facing platform, we will guide you through every step.