🧩

Build a custom web app — exactly the software you need

We build professional websites, apps, online shops and custom systems — with the quality of big agencies but without their overhead. Specialised in Germany's small and medium businesses.

Request a project Message us directly on WhatsApp

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.

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.

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- and BFSG-compliant, hosted on EU servers. You talk directly with the developer — in German, English or Arabic — and in the end the software and data belong to you, with no lock-in.

Typical challenges

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

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

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.

In practice

Real-world examples

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.

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.

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.

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, BFSG 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, English or Arabic. 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

Fixed price before we start. All prices net, plus 19% German VAT. No hidden costs.

Starter Website

from €499

1–3 pages, mobile-optimized, GDPR-compliant

Standard Website

from €999

5–10 pages, blog, contact form

Online Shop

from €1,499

Shopify or WooCommerce, DHL/Hermes, PayPal/Klarna

Booking System

from €799

Online appointments, SMS/WhatsApp reminders

Optional maintenance from €29/month (updates, backups, small changes).

Free initial consultation & a fixed-price quote within 48 hours — no obligation.

Request a project

FAQ

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 per BFSG, 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.

Let's talk

Tell us briefly about your project. We respond within 24 hours.