01What it is
A web application is software you open in a browser, at an address like a website. The difference lies in what you do there. On a website you mostly read. In a web application you work: you log in, enter data, search, approve, upload files and export reports.
Online banking, a CRM, a ticket system, a booking tool and a client portal are all web applications. So are many tools that companies build for themselves, such as an order overview for the warehouse or a dashboard that brings together figures from three different systems.
02How it works
A web application has three parts that work together.
- The screens in the browser. They show tables, forms and charts and react to clicks and typing. They hold no data of their own beyond what they are showing right now.
- The server. It receives every request from the browser, checks who is asking and whether that person may see or change what they ask for, applies the business rules and decides what goes back.
- The database. It stores every record permanently: customers, orders, invoices, comments, and who changed what and when.
03What happens when you click
Say a sales colleague opens a customer and changes the phone number. The browser sends the new number to the server. The server checks that the colleague is logged in and allowed to edit customers, checks that the number is plausible and writes it to the database. It then sends a confirmation back, and the screen shows the new number.
A second colleague who has the same customer open sees the change the next time the page refreshes, or immediately if the application updates live. Nobody had to send a file or merge two versions.
04A typical example
Many companies start with a spreadsheet that grows over the years: a list of projects, a tab per customer, colour codes that only one person understands, and a copy on every laptop. A web application takes over the same job with clear rules.
- Each record exists once, and everyone sees the current state.
- Each person logs in with their own account and sees what their role allows.
- Every change is recorded with name and time.
- Calculations happen in one place on the server, so every user gets the same result.
- Reports and exports come from the same data, as Excel or PDF when someone needs them.
05Compared with other kinds of software
Desktop software is installed on each computer. It can work without an internet connection and use the full power of the machine, which matters for video editing or CAD. Every update has to reach every computer, and the data often sits on one machine or a file share.
Native mobile apps are installed from an app store. They can use the camera, push notifications and work offline well. They have to be built separately for iPhone and Android and go through the stores' review for each update.
Ready-made cloud software, such as a standard CRM, is also a web application, only one that someone else builds for many customers. It is quick to start with and costs a monthly fee per user. It fits well as long as your process matches what the product expects. A custom web application is worth it when your process is what sets you apart, or when you would otherwise pay for several tools and connect them by hand.
06What to watch out for
Most of the questions worth asking before a web application is built are about ownership and operation, and less about technology.
- Who owns the code, the database and the hosting account once the project is finished.
- Where the servers are, and whether personal data stays in the EU.
- How people log in, and how access is removed when someone leaves.
- How data is backed up, and how quickly it can be restored.
- What the application costs to run each month, separate from what it costs to build.
- Whether another developer could take over the code if needed.
07How we build them
Our web applications are written in TypeScript with React and Next.js, keep their data in Postgres and run on servers in Frankfurt, usually at Vercel and Neon. Every person who needs access gets their own login, and what they see depends on their role.
We host in accounts that belong to the client, so at handover the client already owns the code, the database and the hosting. The client pays the providers directly. Every change to the code goes through a pull request on GitHub and automatic tests before it reaches the running application.
Frequently asked questions
Does a web application work on phones?
Yes. The same application adapts its layout to the screen size. For work on the go, such as checking a status or approving something, this is usually enough. A separate app from the app store is only needed for things like offline use or deep access to the phone's hardware.
Does it work without an internet connection?
Usually not, because the data lives on the server. Parts of an application can be built to work offline and sync later, but this adds effort and is only worth it when people regularly work without a connection.
Is a web application less secure than software installed in the office?
Not as such. Security depends on how it is built and run: encrypted connections, proper logins, permissions checked on the server for every request, updates and backups. A well-run web application in a professional data centre is often better protected than a server in a back office.
What does it cost to run?
For a small team, hosting and database often cost somewhere between nothing and a few dozen euros a month. Costs grow with the number of users, the amount of data and paid services such as AI models. We give an estimate for the running costs before the project starts.
Can we connect it to the tools we already use?
In most cases, yes, as long as those tools offer an API. Accounting, banking, mail, chat and file storage services usually do. Our article on APIs explains how this works.