Web applications & platforms

Web applications that scale from MVP to platform.

Customer portals, SaaS products, marketplaces and internal tools with enterprise architecture, security and speed. Live in weeks, not months, at a fixed price per phase.

What we do

Web application development without the overhead of a software house

A spreadsheet shared by 3 departments. A portal your customers were promised 2 years ago. A SaaS idea waiting for a dev team you cannot afford. The question is rarely whether you need a web application, but how to build one without losing half a year and a six-figure budget.

RABZI builds web applications and platforms with the architecture of an enterprise and the pace of a studio: Next.js and NestJS, PostgreSQL, multi-tenancy, roles and permissions, payments through Stripe or Mollie, tests in Playwright. AI speeds up the typing, a senior engineer owns the data model, security and scalability. You work directly with the maker.

We deliver in phases at a fixed price: a working first version in 6 to 8 weeks, then expansion based on real usage. Code, data and environment are yours. Hosting in Europe, GDPR by design, and an MVP that looks like a product, not a prototype.

Platform Plate 03 · WEB APPLICATIONS & PLATFORMS
  • 6–20 weeks to first release
  • 100% ownership of code and data
  • 1 senior point of contact, no handoffs
  • EU hosting and data inside Europe

Components

8 components

What you get.

01

SaaS platform development

Multi-tenant, subscriptions and billing, roles and permissions, API. From your first paying customer to hundreds of accounts on the same codebase.

02

MVP development

The smallest version real customers can use, in 6 to 8 weeks. Built to grow, not to throw away.

03

Customer and dealer portals

Login, documents, orders, status and invoices in one place, connected to your ERP or CRM. Fewer emails, fewer calls.

04

Marketplaces and platforms with payments

Two sides, one transaction: providers, buyers, payouts through Stripe Connect or Mollie, reviews and disputes.

05

Internal tools and admin dashboards

Back offices your team uses every day: fast, searchable, with role-based permissions and an audit log.

06

Progressive Web Apps (PWA)

Installable on the phone, usable offline, push notifications. One codebase for web and mobile, without app stores.

07

Booking and scheduling systems

Reservations, rosters, capacity and payments built to your rules, with calendar integrations and automatic reminders.

08

Legacy application modernization

PHP 5, AngularJS, .NET Framework or Access: we move you to a modern stack step by step, without a big bang.

Delivered

  • Technical design and data model
  • Clickable prototype in Figma
  • Design system and component library
  • Web application in Next.js and NestJS
  • Authentication, roles and permissions
  • REST or GraphQL API with OpenAPI documentation
  • Payments and subscriptions through Stripe or Mollie
  • Automated tests and CI/CD pipeline
  • EU hosting with monitoring and backups
  • Documentation, handover and 30 days of aftercare

How we work

→ Process

How an engagement runs.

  1. 01

    Discovery and architecture

    Weeks 1–2. Users, processes, data model and risks. You get a technical design, a clickable prototype and a fixed price per phase.

  2. 02

    Design and design system

    Weeks 2–4. Screens based on real tasks, not a feature list. A design system that makes every next page faster.

  3. 03

    Build in sprints

    Weeks 3–12. A working release on a staging environment every 2 weeks. You test with real data and adjust course where needed.

  4. 04

    Security, tests and performance

    Continuous. Automated tests, OWASP checks, load tests and monitoring. No release without a green pipeline.

  5. 05

    Launch and continued development

    Final week. Go-live, handover, documentation and 30 days of aftercare. Then keep building through Continuous or standalone sprints.

Why RABZI

Why RABZI for this work.

01

Enterprise architecture, studio pace

Multi-tenancy, roles, audit logs and tests from day 1. Not because you have to, but because rebuilding costs more.

02

Fixed price per phase

Every phase has a scope, a price and a date. You decide per phase whether and how to continue.

03

You work with the engineer

No project manager translating. The person you talk to designs the data model and writes the code.

04

AI-accelerated, senior-reviewed

Claude Code writes and tests alongside us. A senior reviews every line, every migration and every dependency.

05

Yours, without lock-in

Open stack, your repository, your cloud account. Any other team could take it over tomorrow.

06

Grants may apply

New software can qualify for the Dutch WBSO R&D credit. We supply the technical substantiation your application needs.

Pricing

→ Pricing

Pricing for web applications & platforms.

Fixed prices, excl. VAT. Extra work only after approval.

Launch from€12,500

One clear goal, sharply executed. The entry level you keep building on.

  • Customer portal or internal tool
  • Accounts, roles & permissions
  • One core process end to end
  • Hosting & monitoring set up
  • Documentation
Request a quote
Flagship from€49,500

For platforms, multiple brands or markets, and projects where nothing is standard.

  • Multi-tenant platform
  • Enterprise architecture & audit log
  • SSO, 2FA, compliance
  • Scalable infra & CI/CD
  • Roadmap guidance
Request a quote

Work

→ All work

Relevant work

Fleet control · −32% · 98.4% · 1,240 · 14 wks Plate 01 · FLEET CONTROL

Illustrative caseTransport company, Rotterdam · 2025

Real-time planning platform for 140 vehicles

−32% empty kilometers

Orders · 0% · +41% · 14,000 · 11 wks Plate 02 · ORDERS

Illustrative caseRestaurant group (6 locations), Utrecht · 2025

Commission-free ordering and reservation platform

0% commission on owned orders

Portal · −38% · WCAG AA · NEN 7510 · 61% Plate 03 · PORTAL

Illustrative casePhysiotherapy group (4 practices), Gelderland · 2026

Patient portal with online booking and e-consult

−38% phone calls at the front desk

Frequently asked questions

Questions about web applications & platforms.

01How much does web application development cost?

A web application from RABZI starts at €12,500 excl. VAT (Launch: a portal or tool with one core process). Growth from €24,500 is a SaaS MVP with accounts, payments and an API. Flagship from €49,500 is a multi-tenant platform with integrations and multiple roles. Every phase has a fixed price. For comparison: software houses quote €25,000 to €60,000 for a comparable MVP.

02How long does it take to build a web application?

A first working version is on a staging environment in 6 to 8 weeks and goes live after that. A SaaS MVP with payments and an API takes 10 to 14 weeks, a platform with multiple roles and integrations 16 to 20 weeks. We work in 2-week sprints, each ending in a release you can use, so you adjust early instead of being surprised at the end.

03What is an MVP and why start there?

An MVP (minimum viable product) is the smallest version of your platform that helps real users. You build the one process that creates value first, measure how it is used and expand based on facts instead of assumptions. That often saves half the budget that would otherwise go to features nobody uses. We build an MVP on an architecture that already handles the next phases.

04Custom build, low-code or off-the-shelf SaaS?

Off-the-shelf software wins when your process is standard. Low-code wins for quick internal experiments, but per-user licenses and limitations grow with you. Custom wins when the application is your edge, when your customers use it, or when you need integrations and scale. With AI-assisted development, custom has become 3 to 10 times cheaper than 5 years ago. We advise honestly, even when the answer is an existing product.

05Who owns the code and where does the application run?

You do. The code lives in your repository, the application runs in your cloud account (Hetzner, Azure or AWS in Europe) and every account is in your name. There are no RABZI licenses and no dependency on us to keep building. We document the architecture and decisions so any senior team can take over. Most clients simply choose not to.

06How do you handle security and GDPR?

Security is part of the design: encrypted storage, roles and permissions, audit logs, OWASP checks in the pipeline, dependencies under control and hosting in the EU. Personal data is processed under GDPR, with a data processing agreement and data minimization as the default. For sectors with extra requirements, such as healthcare or finance, we set up MFA, SSO and logging and work with a certified partner for penetration testing.

Knowledge

→ All articles

Keep reading

Reply < 1 business day · Available for new projects

Ready to build your platform?

Tell us what the application needs to do and for whom. You will hear back within 1 business day and have a proposal with architecture, phases and fixed prices within a week.

info@rabzi.nl · ...