Hi, I'm István Kappelmayer 👋

Built and operate a multi-tenant IoT and digital signage platform in AWS Zurich, in production across 14 stacks for API, auth, portals, player, transcoding, scheduler, observability, security and DNS

Infrastructure as Code throughout with AWS CDK, separate dev, test and prod environments, configuration-driven deployment with a production checklist

Device fleet over AWS IoT Core and MQTT: certificate-based identity, self-enrollment, remote maintenance, self-healing of failed devices, Android kiosk firmware with zero-touch provisioning and self-update

Security hardening and compliance: Swiss revDSG, PCI DSS SAQ A, CE/RED as the entity placing the product on the market

End-to-end conception and build of a revDSG-compliant Swiss cybersecurity assessment SaaS (scmc.ch), live in AWS Zurich since November 2025, ten assessment modules from ISO/IEC 27001 and NIST CSF 2.0 to the Swiss ICT minimum standard, NIS2 and DORA

Serverless architecture: Quarkus Native Lambda backend on GraalVM, DynamoDB single-table, Cognito, Vue 3 frontend, payment flow via Stripe

CI/CD with GitHub Actions across separate AWS accounts for dev, test and prod, role assumption via OIDC without long-lived credentials, Infrastructure as Code with AWS CDK

Independent software practice: customer portals, serverless platforms, custom SaaS and back-office automation on AWS, plus AWS Well-Architected health checks as standalone audits

Vendo Swiss Solution AG (2026): migration of the company platform to AWS, in production since July 2026; architecture of the parcel-box platform with its Swiss Post integration, including the connectivity and scaling concept; technical lead of an external development team

Kitti Kovacs Design Ltd, UK (2026, in build): rebuild of the website of an award-winning garden designer, off WordPress and onto Astro SSG, with a photographer credit on every image and a serverless enquiry backend on AWS

Munot (2026): web analytics from server logs with classification and IP verification of AI crawlers, CloudFront logging to S3, Quarkus Native Lambda, multi-tenant DynamoDB

Regiowerber.ch (2026): own self-service portal for local advertising on public screens, small businesses pick screens near them and book by the day; built and operated end-to-end, Vue 3 and a serverless backend with Lambda and Cognito in AWS Zurich, card and TWINT payment via wallee

Rentaside (2024): neighbourhood rental marketplace, iOS and Android with React Native and Expo, AWS serverless backend, build and deployment pipelines with GitHub Actions

APN alliance lead, building the AWS partnership up to Select tier, technical support for sales and marketing

End-to-end application migrations into AWS: Oracle Enterprise to Amazon RDS, 17 J2EE modules from WebSphere onto Payara Micro in ECS Fargate, cost and CO2 optimisation through ARM architecture

Authentication@Edge with CloudFront, Cognito and Lambda@Edge, API management for third-party access, VPN connectivity between AWS and the on-premise data centre

DevOps consulting for customer teams: GitLab CI/CD, Vault for secrets, application operations on OpenShift, Amazon EKS provisioned via Terraform, Helm charts and Argo CD for declarative GitOps

Planned and implemented cloud architectures based on customer requirements

Delivered AWS trainings for professionals and corporate clients

Created and presented cloud PoCs for public and hybrid cloud solutions

Designed and implemented an OpenShift-based DevOps environment with full CI/CD automation, plus an AWS-based development environment

Modernized J2EE applications to microservices with Spring Boot and Quarkus

Maintained and extended an application in the import/export process of Swiss Post, supporting autonomous-driving research

Ownership of three applications, architecture of new modules

Migrated legacy systems to microservices using Spring and MongoDB

Developed REST APIs and AngularJS frontends within an enterprise framework

Coordinated distributed teams across the US, Germany and offshore locations

Telecom applications for a major provider: visualisation of physical wiring and DSL termination networks

Development with Eclipse RCP, WebSphere, Spring and WebSphere MQ

Offshore coordination and knowledge transfer

Designed and implemented national-scale Java enterprise systems for pension insurance and government digital services

Led backend integration projects across AS400, Windows, and Java systems using WebSphere ESB and MQ.

Developed secure XML-based digital signature and timestamping solutions for government documents using PKI, XAdES, and Java Cryptography (PKCS#7, PKCS#12).

Co-developed a banking system and a credit scoring system with server-side Java, Tomcat and JSP

Trading system for pharmacies, a 3-tier system in Delphi 7 on Firebird SQL Server

Extended a trading system with new modules and applications: SMS sending and receiving over a GSM terminal, an asynchronous data processor, POP3 and SMTP clients

Co-developed a banking system with server-side Java, Tomcat and JSP

Built a trading system, developed a BDE alternative and a 3-tier application server