Christian Hutzinger-Freelance Software Developer · Payment & Ticketing Systems · PHP / Go
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Experience
Senior Full Stack Developer
Adria Magazin GmbH
Jesolo Tickets – Booking platform for tickets
Concept and implementation of a multi-tenant booking platform for the online sale of bus and ferry tickets in the Jesolo region (Northern Italy). Travel agencies and event organizers embed a customizable booking widget on their own websites; travelers check live availability, book multiple passengers, and pay online in just a few clicks.
- Real-time booking: Schedules and prices come live via the transport providers' API; after payment, the tickets are automatically delivered as QR-coded PDFs – with no manual issuance.
- Provider architecture: New providers can be onboarded without code changes; an origin-based multi-tenant model with its own domain and payment configuration for each partner site makes the platform grow with every customer.
- Clean architecture: 3-tier structure (handlers → services → data store) with caching – availability checks stay fast and maintainable even with many parallel requests.
Tech stack: Go, Echo, PostgreSQL (pgx), Stripe, Web Components, Tailwind CSS, esbuild, Docker, GitLab CI, Hetzner VPS
Senior Full Stack Developer
mtms Solutions GmbH
Co-development and maintenance of a SaaS platform for ticketing and events – with a focus on payment and wallet integrations, process automation, and custom applications.
- Ticketing platform: Covers the entire event lifecycle in one system – from setup through online sales and box office operations to admission control and reporting, with digital tickets as Apple/Google Wallet passes; supports events from small gatherings to large-scale events.
- Payment gateway: Development of the central gateway through which all ticket sales are processed – connected to Stripe, Payone, CCV, PayPal, Klarna, Apple Pay, and Google Pay; monitored in production with Sentry and Grafana.
- Automated payment reconciliation: Replaces the error-prone manual CSV matching with rule-based matching of bank transactions (Open Banking / PSD2) with automatic finalization, ticket delivery, and detection of duplicate and incorrect bookings – reconciliation runs without staff involvement.
- APIs & Box Office: RESTful APIs connect system components and external services; through the integration of payment terminals, on-site box office operations become part of the same continuous sales flow.
- Document review (logistics): Web application for a large German logistics company – from upload through approval to audit-proof archiving – with role-based permissions and complete logging. Replaces the paper-based approval process and makes every step traceable.
Tech stack: PHP, Laravel, Vue.js, JavaScript, TypeScript, Python, MySQL, Omnipay, REST, OpenAPI / Swagger, Sentry, Prometheus, Grafana, GitLab, YouTrack
Senior Full Stack Developer
atms GmbH
Backend development in messaging and mobile payment – from multi-channel publishing to automated service hotlines and gateway architecture.
- Multi-channel publishing CMS: A message reaches SMS, Facebook, Twitter, and app push at the same time – with automatically branded images for the Facebook feed, predefined send times, and queue-based delivery; used by a large radio station in the German-speaking region, which reduces editorial effort per update to a single process.
- Disposal & service hotline: IVR system that prevents duplicate orders and automatically calculates the contractually correct pickup date from branch- and country-specific rules and passes it to the right waste management provider – multi-tenant across more than ten countries and languages, built for a large European grocery retail chain.
- Mobile payment & gateway architecture: Expansion of the central messaging and payment gateways for high-volume traffic – with a focus on scalability and real-time performance so the gateways remain reliable even under peak load.
Tech stack: PHP, Laravel, Vue.js, JavaScript, MySQL, Java, Python, C++, IVR, REST, Git, Jira, Confluence
Full Stack Developer
mobileworx trading GmbH
Focus on mobile network integration and mobile messaging: connection of mobile operators and building the mobile payment and messaging infrastructure.
- Mobile messaging: Reliable SMS/MMS delivery across operators and borders – connection to European mobile operators via SOAP, XML-RPC, and REST through a single interface.
- Mobile payment solutions: Building and maintaining the mobile payment gateway infrastructure with direct operator connection – enabling secure carrier billing and payment processing as the basis of the mobile payment business.
Tech stack: PHP, Java, JavaScript, MySQL, Tomcat, C++, SOAP, XML-RPC, REST, Git, Jira, Confluence
Industry Experience
See where this freelancer has spent most of their professional time.
Experienced in Information Technology, Telecommunication, Transportation, Media and Entertainment, Retail, and Tourism.
Business Area Experience
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Experienced in Information Technology, Product Development, and Operations.
Summary
For over 20 years, I have been developing payment and ticketing systems as well as SaaS solutions. I also build custom web and backend applications – from requirements through development to operations. My focus areas are payment integrations, system connections, and RESTful APIs. My core stacks are PHP/Laravel and Go: Laravel for fast, maintainable web and SaaS development, Go for high-performance services and gateways.
Skills
Payment & Gateways: Integration Of Stripe, Payone, Ccv, Paypal, Klarna, Apple Pay, Google Pay, And Mobile Operator Apis.
Gateway Architecture: High-Load Gateways For Payment And Transaction Processing – Scalable And Reliable.
Full Stack & Apis: End-To-End Solutions With Php, Laravel, Go, Javascript/Typescript; Design And Implementation Of Restful Apis.
Digital Wallets & Tickets: Apple And Google Wallet Integration For Digital Tickets On Mobile Devices.
Custom Software Projects: Implementation Of Custom Web And Backend Applications – From Requirements Through Development To Operations.
Languages & Frameworks: Php · Laravel · Go · Echo · Javascript · Typescript · Vue.Js · Python
Databases: Postgresql · Mysql
Payment & Apis: Stripe · Payone · Ccv · Paypal · Klarna · Apple/Google Pay · Rest · Openapi / Swagger · Soap · Xml-Rpc · Apple/Google Wallet
Infrastructure & Devops: Docker · Gitlab Ci · Hetzner Vps · Coolify Paas · Open Banking / Psd2 · Sentry · Prometheus · Grafana
Tools: Zed · Phpstorm · Goland · Pycharm · Gitlab · Youtrack · Slack
Methodology: Agile · Kanban (Youtrack) · Ci/Cd (Gitlab)
Languages
Education
HAK / HAS Oberndorf
Business Administration · Salzburg, Austria
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Experience
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Profile
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