Build a custom web app — exactly the software you need
- from €4,900 net
In short
A custom web app starts at around €4,900 net for a clearly bounded MVP (e.g. internal tool, client portal, management system). We build agile, in professional quality, with EU hosting — affordable for small and medium businesses.
Fixed price from€4,900net
Price- Fixed pricein writing before we start
- Hosting in the EUservers and backups in the EU
- GDPR-compliantprivacy built in from day one
- Accessiblefollowing WCAG 2.1 AA
- From Düsseldorfstraight from the developer
Overview
Sometimes no off-the-shelf software fits what your business actually needs — you fight with spreadsheets, juggle several tools and tape everything together by hand. A custom web app maps your exact process: reachable through the browser, with no installation, from any device and any location.
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Rhein Code builds tailor-made web apps for small and medium businesses in Germany — customer portals, internal tools, dashboards, management systems and platforms that simply don't exist off the rack. We listen first, understand your workflow and build software that truly fits, instead of forcing you into someone else's logic.
We deliver at a fixed price from 4,900 € net, GDPR-compliant and accessible (WCAG 2.1 AA), hosted on EU servers. You talk directly with the developer — in German or English — and in the end the software and data belong to you, with no lock-in.
Sound familiar?
- Off-the-shelf software never quite fits — you pay for 80% you don't use
- Your processes live in Excel files and in a few people's heads
- Big agencies quote five- to six-figure sums for custom software
Your web app
Your processes in one application instead of ten Excel files
Orders, customers, documents and reports in one place – in the browser, without installation, with roles and permissions for every team member. Built around your processes, not those of an off-the-shelf product.
What we build as a web app
- Internal tools (management, planning, reporting)
- Client portals with login (orders, documents, status)
- Dashboards that finally make your data clear
- Scalable, secure, GDPR-compliant — hosting in the EU
From our work · TrueAuto
Data-driven car portal for Germany
Technical data, prices, costs and reliability for more than 800 models, comparisons, an AI adviser and its own vehicle marketplace – data model, website and marketplace built and operated by us.
84 brands · 819 models
Custom Web Apps
What your website or solution delivers
Tailored business logic
We implement your exact workflows — calculations, approvals, statuses, rules — instead of bending you to the limits of standard software. The app speaks your business's language.
Browser-based, no installation
Your web app runs in the browser on laptop, tablet and phone — nothing to install or update. Staff and customers access it securely from anywhere.
Users, roles and permissions
Fine-grained permissions ensure everyone only sees and does what they're allowed to. Admins, teams and customers each get their appropriate view of the data.
Dashboards and reporting
Live overviews, filters and exports turn data into real decisions. You see metrics, orders or stock at a glance instead of in scattered spreadsheets.
Interfaces and integrations
We connect your web app to existing systems — payment, accounting, CRM, email or external APIs. That creates a continuous flow instead of manual double work.
Customer and staff portals
Give customers a self-service portal for orders, documents or status, and staff an internal tool for daily work. Calls and email ping-pong noticeably decrease.
Security and backups
Encrypted connections, thought-through access control and regular backups on EU servers are standard. Your business data is protected and recoverable.
Grow step by step
We often start with a clear first version and extend modularly once you're working with it. You invest deliberately and see results early, instead of a giant project shot in the dark.
Cost
How much does it cost to have a web app built?
We start custom web apps from €4,900 net at a fixed price – for a clearly scoped first release (MVP). What your project costs in the end mainly depends on these six factors. We go through them together in the first call, then you receive a binding quote.
Roles and views
An internal tool for one team is faster to build than a portal where admins, staff and customers each need their own screens and permissions.
Integrations
Every connection to accounting, payment providers, a CRM or an existing database takes effort – but saves duplicate work and typos later.
Data migration
If existing spreadsheets or data from a legacy system need to move over, we plan cleanup and import from the start.
Your business logic
Pricing rules, approvals or reports that follow your rules are the real value of custom software – and the biggest effort driver.
Design ambition
A clean, simple working tool for your own team costs less than a customer portal with full branding.
Hosting and maintenance
Hosting on EU servers, backups, updates and support are priced separately and transparently – no per-user licence fee.
Decision guide
Custom web app, off-the-shelf software or an app-store app?
Not every problem needs custom software. This overview helps you decide – and if an off-the-shelf product fits you better, we'll tell you honestly in the first call.
| Criterion | Custom web app | Off-the-shelf (SaaS) | Native app (iOS/Android) |
|---|---|---|---|
| Fits your process | Exactly – built to your rules | Only if your process is standard | Exactly, but built per platform |
| Upfront cost | One-off, from €4,900 net | Low | Usually higher (iOS and Android) |
| Running cost | Hosting and maintenance, no per-user licence | Monthly licence, often per user | Hosting, maintenance, app-store fees |
| Installation | None – runs in the browser | Usually none | Download from the app store |
| Devices | PC, tablet and smartphone | Depends on vendor | Smartphone and tablet |
| Data and code | Belong to you | Stay with the vendor | Belong to you |
| Best for | Internal tools, customer portals, processes with your own rules | Standard tasks like accounting or email | Offline use, camera, field service |
Examples
Typical scenarios
Example 1/4
A business drowning in spreadsheets
Orders, statuses and handovers run through scattered tables nobody can keep track of any more. A web app bundles everything in one place with clear roles and real-time status.
Example 2/4
A provider that needs a customer portal
Customers constantly ask for status, documents or invoices by phone and email. A self-service portal gives them round-the-clock access and relieves the team enormously.
Example 3/4
A team with too many single tools
Several siloed solutions get taped together by hand, data is maintained twice and errors creep in. A tailor-made app links the steps into one clean flow.
Example 4/4
An idea that should become a platform
A business model with no ready-made software needs its own system as a foundation. We build a first viable version and grow it together with you.
Rhein Code
Why Rhein Code for Custom Web Apps
Fixed price, not an open hourly tab
You get a clear quote from 4,900 € net, matched to the agreed scope — no endless hour counter. Larger ventures are split into plannable stages.
Software that truly fits
Instead of squeezing your process into someone else's tool, we build exactly what you need. Long term, that saves the workarounds and licence costs standard software drags along.
GDPR, accessibility and EU servers
Data protection, accessibility and EU hosting are built in from the start, not bolted on afterward. For your own systems holding real business data, that's decisive.
Direct contact with the developer
You talk to the person building your app, not a call centre, in German or English. Domain details land directly where they get implemented.
No lock-in, full ownership
The app, the data and, on request, the source code belong to you. You can keep developing it any time — with us or with someone else.
Process
How we work
MVP workshop
We define the smallest valuable feature set.
Fixed-price quote
Clear MVP scope at a fixed price — no open-ended hours.
Agile development
Working versions every 1–2 weeks, early feedback.
Launch & evolution
Stable operation, then expansion as needed.
Technology & standards
- React / Next.js
- Node / .NET
- PostgreSQL
- Auth & roles
- EU servers
- CI/CD
Fixed price
Transparent pricing
Custom Web Apps from€4,900net
Fixed price plus 19 % VAT, in writing before the project starts. The exact price depends on scope.
Optional maintenance from €29/month (updates, backups, small changes).
What's included
- Internal tools (management, planning, reporting)
- Client portals with login (orders, documents, status)
- Dashboards that finally make your data clear
- Scalable, secure, GDPR-compliant — hosting in the EU
Free initial consultation & a fixed-price quote within 48 hours — no obligation.
Request a projectFAQ
Frequently asked questions
What does a custom web app cost?
We build a tailor-made web app at a fixed price from 4,900 € net (plus 19% VAT). The price depends on scope and complexity — simple internal tools sit at the lower end, extensive platforms higher. After a short conversation you get a clear, binding quote.
How does a project like this run?
We start with a conversation about your workflow and your goal, define the scope, then deliver a first usable version. After that we extend modularly, so you can test and give feedback early.
How long does development take?
It depends heavily on scope. A focused first version is often ready within a few weeks, larger platforms come in several plannable stages. We give you a realistic timeframe upfront.
Do I own the app and the source code?
Yes. The software and data belong to you, and the source code is available on request. There is no lock-in — you can keep developing the app any time, with us or a third party.
Can the app connect to other systems?
Yes, that's often the core. We integrate payment providers, accounting, CRM, email or external APIs wherever an interface exists. We clarify which integrations make sense at the start.
Is the app GDPR- and accessibility-compliant?
Yes. We build privacy-compliant per GDPR and accessible to WCAG 2.1 AA, hosted on EU servers. For your own systems holding real business data, we implement this from the very start.
Can we extend the app ourselves later?
Yes. We build cleanly structured and documented, so extensions are always possible — by us or your own team. You manage content and master data yourself through the interface anyway.
Does the app work on mobile too?
Yes. Rhein Code web apps are responsive and run in the browser equally on phone, tablet and desktop. No installation is needed.
What is the difference between a website and a web app?
A website informs – visitors read and get in touch. A web app is a tool: users log in, edit data, trigger processes and see their own status. Both run in the browser, but a web app contains your business logic.
Web app or app-store app – which is better?
For internal tools and customer portals a web app is usually enough: no installation, one codebase for every device, lower cost. A native app pays off when offline use, the camera or push notifications in the field are essential. We build both and recommend what fits your case.
What do you need from me for a quote?
A short description of your process, who will use the app, which systems you use today and ideally an example of your current spreadsheet or forms. From that we scope the first version and give you a fixed price.
Do you only work with companies in Düsseldorf?
No. We are based in Düsseldorf and deliver projects for companies across Germany. We coordinate by email and video call – and you always talk directly to the developer.
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Contact
Let's talk
Tell us briefly about your project. We respond within 24 hours.
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