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Rapcsány Krisztián Rapcsány Krisztián
hu
Full stack developer

I build systems
that work.

As a full stack developer with 10+ years of experience, I own your project end to end: backend, web interface, mobile app and operations, from the first idea to production, and beyond.

Or start with a system audit
Rapcsány Krisztián
10+
years of experience
Full stack
backend, frontend and mobile
Design
small and large systems
CTO
I have built and led a team too
Services

How I can help

Custom software

Systems shaped around your business processes, not off-the-shelf compromises.

Website development

Fast, secure, easy-to-maintain websites and web applications.

Small and large features

A new feature, an integration or a full module, even as a one-off task, whatever the size.

Live system maintenance

Operating, fixing and continuously extending systems that are already running.

Optimisation and scaling

Designing and speeding up high-load systems: caching, message queues (Redis, RabbitMQ), asynchronous processing and database tuning.

Mobile apps

iOS and Android apps, from design to the app stores.

Legacy refactoring and redesign

Gradually rewriting old, hard-to-maintain systems with a live cut-over, while preserving existing behaviour.

Consulting and system design

Preparing architecture, data model and technology decisions, so the system stays extensible and cheap to maintain.

Diagnostics and audit

Reviewing an existing system: uncovering bugs, slowdowns, security and maintainability risks, with prioritised recommendations.

How we can start

Three ways to get going

Recommended start

System audit

I review your existing system and tell you what is wrong, how risky it is, and what is worth fixing first.

  • Review of code, database, performance and security
  • A prioritised issue list and a proposed next step
  • A walkthrough call, with no obligation
How the audit works →

New system or MVP

From an idea to a working product: design, development, go-live. We build the essentials first, then extend.

  • Requirements turned into a system design
  • Regular demos, so you see where we are
  • Handover and documentation, and I am around afterwards
Tell me about my idea →

Extending an existing system

Extending a live system, fixing bugs, speeding it up, or gradually rewriting old code while it keeps running.

  • New features and integrations
  • Performance and bug fixes
  • Legacy refactoring, with a safe cut-over
What needs developing? →
Projects

Featured projects

An example of a good ecosystem

Not separate apps, but one connected system

Web platform Customer mobile app Check-in app Point of sale Payment and invoicing Media server Administration Statistics and campaigns
An example of a good ecosystem

Web platform

The core of the system: catalogue, cart, payment, ticket issuing and API. Everything else connects to it.

Hover or tap a node to see what it is connected to.

Background

Full stack skills, in one pair of hands

PHP and Laravel

Deep expertise. This has been my main field for years.

Database systems

Solid knowledge: design, optimisation and handling large data volumes.

Frontend and mobile

HTML, Twig, JavaScript and React Native: the interface and the app are as polished as the backend.

High-load systems

Experience with systems where performance and stability matter.

Operations

Background jobs, message queues (Redis, RabbitMQ), caching, scheduling and health monitoring: the system runs steadily in production.

Integrations

Payments, invoicing, email, push notifications and external systems, tied together into one coherent whole.

Technologies

Backend
PHP 8.x Laravel 12 Queues and events RabbitMQ Permission systems Feature flags
Mobile
React Native Expo TypeScript iOS Android OTA updates
Real-time
Laravel Reverb Echo WebSockets Pusher-js
Authentication
Sanctum JWT Socialite (OAuth)
Integrations
REST API Webhooks SOAP Payment providers Third-party APIs External systems Swagger / API docs
Database and cache
MySQL / MariaDB PostgreSQL MongoDB / NoSQL Redis Stack and Search
Media and documents
FFmpeg HLS streaming Image processing (WebP) PDF generation Excel export QR codes
Frontend
Blade Twig Smarty Tailwind Bootstrap 5 SCSS / SASS / LESS JavaScript jQuery Vite WordPress
Version control and deployment
Git GitLab GitHub Deployer CI/CD
Infrastructure
Docker Docker Compose Deployment pipelines Jira
Process

How we work together

  1. 01

    Conversation

    I learn your goals and constraints. The first call is free.

  2. 02

    Proposal

    A clear plan, timeline and price, with no surprises.

  3. 03

    Development

    Regular demos, so you always see where we are.

  4. 04

    Handover and support

    I stay with you after the go-live.

FAQ

What is worth knowing before we start

Do you work at a fixed price or on a time budget?

It depends on the task. If it is well defined, I give a quote with an agreed scope. If it may change or needs research, we work on a time budget. At the start I always write down what is included.

How fast do you reply?

Usually within 1 business day. If it is urgent, say so in your message.

Do you work on existing systems too?

Yes, that is most of my work: extending live systems, fixing bugs, speeding them up and redesigning old ones. First I go through the code and tell you what I see.

Do you work alone or in a team?

Normally alone. For bigger jobs we can work as a team, and I have led a development team before.

What happens after handover?

You get documented code and a handover. If you want, I can take on maintenance and further development afterwards, but it is not required.

How do we work together if we are far apart?

I work remotely. We talk over video, phone or in writing, and you follow progress in regular demos.

Have an idea, or a system that needs work?

Write a few lines and I will reply within 1 business day.

Get a quote →