Web applications · custom in the browser
A web application is software that runs in the browser and that your team works in: processing orders, managing records, planning or giving customers their own portal. No installation on each workstation, always the latest version, reachable anywhere with a login.
MG Software in Haarlem has been building custom web applications since 2018. We translate a process that now drifts across Excel, email and disconnected tools into a system that takes control, prevents errors and grows with you.
This page explains which web applications we build, what they cost, how long they take and when a custom web app is smarter than an off-the-shelf package. Honestly and without jargon.
No two projects are the same, but these are the forms we deliver most often.
A system that replaces a stuck Excel process: orders, inventory, scheduling or time tracking in one place, with role-based permissions and a log of who changed what.
A secured environment where your customers view and manage orders, documents, invoices or appointments themselves, without phone calls or email threads.
Real-time insight into figures now scattered across multiple systems. One overview decisions are made on, instead of exported spreadsheets.
Ordering and service platforms where your business customers and partners handle transactions themselves around the clock, connected to your back office.
Requests, checks and approvals that now run over email, captured in a system with clear steps, notifications and a complete trail.
A central place for relations, subscriptions or memberships, linked to billing and communication, so double entry disappears.
These three are often confused, while the difference determines what you have built. A website exists to show information and convince visitors. A web application exists to work in: users log in, enter data and perform tasks. A native app is installed from the App Store or Google Play onto a phone.
If your users mainly read, you need a website. If they enter and edit data and run through processes, it is a web application. Unsure between a web app and a native app, the rule of thumb is simple: if the software has to work on any device with a browser without installation, choose a web application. If you need camera access, push notifications or heavy offline functionality, a native app comes into play.
In practice a responsive web application solves by far the most business needs. It works on desktop, tablet and phone, can be updated instantly and needs no app store approval for every change. Still unsure? We map it out for you in a short conversation.
We work in clear phases so you always know where the project stands, what comes next and when you can steer.
Map goals, users and existing landscape. We identify risks and opportunities before any code is written.
Wireframes, clickable prototypes and visual design. You see the product before a developer starts.
Build in two-week sprints with working demos. Every sprint delivers something testable.
Functional tests, performance checks and security review before your users see it.
Deployment with monitoring setup, error logging and a rollback plan when needed.
Maintenance, version management and iteration based on user data. Software is never done.
A well-scoped internal web application that replaces a single process realistically starts around 15,000 to 30,000 euros. Think of a tool that turns a shaky Excel file full of formulas and loose tabs into a real system with users, permissions and a database that does not break the moment two people work at once.
A more extensive platform with multiple user roles, a customer portal and integrations with existing systems sits more between 40,000 and 90,000 euros. The price within that range is driven by the number of screens, the complexity of the business logic and how many external systems you want to connect.
We only name a figure after a short discovery in which we map your process. A quote based on a phone call sounds customer-friendly, but almost always leads to surprises later. For a first indication you can use our calculator.
If an off-the-shelf package exists that does exactly what you need, we tell you honestly. We earn nothing from unnecessary custom work. Custom becomes interesting only when you notice you are bending a tool to fit your process instead of the other way around.
The signal is almost always the same: workarounds, spreadsheets alongside the package, manual export-imports and tools held together with tape. At that point the standard software costs you more time than it saves, and a web application built around your process brings immediate calm.
A hybrid approach is fine too. Use existing services for what is generic, like accounting or email, and build only the part custom that sets your business apart. That way you do not pay for custom work where a ready-made solution does the job.
We choose the stack based on your problem, not based on hype.
React / Next.js
Web & frontend
React Native
Cross-platform mobile
Node.js / Bun
Backend & APIs
PostgreSQL
Relational data
Supabase
Auth, storage, realtime
Vercel / AWS
Hosting & CDN
Stripe / Mollie
Payments
OpenAI / LLMs
AI integrations
Related services and background covering specific decisions in more depth.
A website shows information, a web application lets people work. On a website a visitor reads pages; in a web app someone logs in and performs tasks: processing orders, maintaining records, planning, running reports. Technically a web app is more interactive, works with user accounts and permissions, and runs on a database that is continuously updated. Unsure whether you need a website or a web app? If your users mostly enter and edit data rather than read, it is almost always a web application.
A simple internal web application that replaces an Excel process realistically starts around 15,000 to 30,000 euros. A more extensive platform with multiple user roles, integrations with existing systems and a customer portal sits more between 40,000 and 90,000 euros. The price is driven by the number of screens, the complexity of the business logic and how many external systems you want to connect. We only quote after a short discovery, because an estimate without knowing the processes is almost always misleading.
A first working version of a well-scoped web application is usually delivered in 6 to 10 weeks. A fuller platform with multiple modules runs to 3 to 6 months. We work in two-week sprints, so after every sprint you see a working version and can steer before we build too far in the wrong direction.
Yes. We build web applications responsively, so they work on desktop, tablet and phone through the browser, without your staff installing anything. For field use we can set the web app up as a progressive web app (PWA), giving it its own icon and limited offline capability. If you specifically need a native app for the App Store or Google Play, we discuss that route on our custom app development page.
Almost always. We connect web applications daily to accounting packages like Exact Online, to CRM systems, webshops and payment providers. If a system has an API, we can connect it; if it does not, we look for an import or export route. The integration is often exactly why a web app delivers value, because double entry and manual retyping disappear.
The code is yours. We set the web application up on your own hosting and cloud accounts and deliver the repository to your GitHub organisation. That way you are never locked in to us as the only party with access. For hosting we typically use Vercel or a European cloud, depending on your requirements around data storage and GDPR.
A web application needs periodic maintenance: security updates, keeping dependencies current and small improvements based on usage. We offer maintenance plans with a fixed number of hours per month, but you are not obliged to anything. Because the code and infrastructure are yours, you can also place maintenance elsewhere.
You build a web application for your own organisation or your customers: an internal system, a portal or a dashboard supporting a specific process. You build a SaaS product to sell as a service to many different customers, with subscriptions and multi-tenancy. The technology overlaps, but the choices around billing, customer isolation and scalability differ significantly. If you want to sell software rather than use it, see our build a SaaS page.
Half an hour is enough to determine whether a web application genuinely improves your process and roughly what it costs. You get an honest estimate at the end, even when it differs from what you hoped to hear.