Architecture and integration
End-to-end solution design: API gateways, central authentication (OAuth2, JWT, Entra ID), messaging, and connecting ERP, CRM and web systems.
Lunabyte · Rastislav Janotka
Architecture and integration that actually work.
Solution architect and senior backend developer. For almost 30 years I have been designing and delivering integration solutions for large enterprises, from telecom and banking to EU institutions.
About
Who is Lunabyte
Lunabyte is my consulting company. I specialise in end-to-end architecture: from IoT devices and streaming platforms through API gateways, central authentication and message-driven integrations, to connecting enterprise systems with SharePoint.
I build backends mainly in Jakarta EE, Spring Boot and Go, and reach for Rust where the situation allows. I have repeatedly led legacy migrations to modern cloud-ready solutions and advised company leadership, including independent reviews of vendor proposals.
0years of experience (since 1996)
0sectors: telecom, banking, insurance, EU institutions
0companies and institutions in SK, CZ, DE, BE and LU
Services
How I can help
From design to production, or just an independent expert opinion before you sign a contract.
AI consulting
Finding where AI genuinely pays off. Reviewing vendor proposals for price, vendor lock-in and security. Coaching teams in everyday practical use of AI.
Backend and legacy migration
Development in Java, Go and Rust. Legacy migrations, upgrades (Java 11 → 17 → 21), CI/CD, Docker and fixing security findings.
Web, e-shops and SEO
B2B catalogues and e-shops, POHODA integration, technical SEO, structured data, and GDPR and cookie compliance done properly.
Experience
The road since 1996
A selection of client and employer engagements. The full CV is available on request.
2026 – …
Technical consultant and full-stack developer
SEPRON BB s.r.o.
POHODA ERP integration over XML API, rebuild of an e-shop into a B2B catalogue, technical advice for leadership and independent review of agency proposals.
2022 – 2025
Senior Java Backend and Integration Developer
Deutsche Telekom / T-Systems
Migrated a SharePoint connector to Jakarta EE, SPFx extensions, Entra ID authentication and automated CI/CD in an international team.
2017 – 2022
Solution Architect and Lead Developer
Xmusix / Yomie
Audio streaming platform for IoT set-top boxes: API gateway in Go, central authentication, HLS streaming and the full infrastructure.
2015 – 2017
Backend developer, GDPR and archiving
T-Com Slovakia (Slovak Telekom)
Archiving solution with a WebSocket protocol and Alfresco (CMIS). Designed the personal-data removal procedure across critical systems (Cramer, Genoa, Vitria, Siebel).
2012 – 2014
Developer and analyst
XmusiX Distributions
CRM/CMS for distributing music and advertising audio to venues. Architecture, data model and custom audio UI components.
2009 – 2012
Developer and analyst
Datalan (VÚB, Orange, T-Com)
Enterprise applications on JBoss, web services and JSF. Projects: Orange Web Shop, VÚB Hypo, T-Com hosting migration.
2006 – 2008
Java developer and analyst
Ľudová banka · Allianz · WV Leasing
Internet banking, leasing applications and Lotus Notes prototypes ported to Oracle.
1996 – 2004
Web developer and analyst
European Parliament · Dronex · HTC
Intranet applications for the European Parliament in Luxembourg and Brussels, Lotus Domino/Notes workflows and PHP/ASP solutions.
Technology
Tools of the trade
I pick language and framework by the job, not by fashion.
Languages
JavaGoRustTypeScriptPythonC#PHPSQLBash
Backend and integration
Jakarta EESpring BootRESTWebSocketJMSAPI gatewayMS GraphSharePoint SPFx
Security and IAM
OAuth2JWTOpenIDAzure AD / Entra IDS2S authTLS / PKI
Data and messaging
PostgreSQLOracleMySQLMongoDBRedisRabbitMQArtemisKafkaNeo4j
DevOps and infrastructure
DockerKubernetesHelmJenkinsGitLabNginxCaddyLinux
AI and data processing
OllamaRAGWhisperMCPEmbeddingsKnowledge graphSandboxing
Frontend
Vue 3ReactAngularAstroHTML5 / CSS
ERP, web and media
POHODA XML APIWordPress / WooCommerceShoptetJSON-LDffmpegLiquidsoap
Projects
What I build on the side
My own experiments, which then inform client work.
Hybrid multimodal RAG over a knowledge graph
A personal AI stack running entirely locally with no external APIs: Whisper, Ollama, Neo4j, Vue 3 and Kubernetes deployment via Helm. An experiment in when a graph beats a classic vector database.
Custom tools in Rust
Utilities and integration tools focused on performance and memory safety: Google OIDC, Kafka and data pipelines. To be shown as case studies.
Audio streaming platform with IoT
Set-top boxes with custom firmware, an API gateway limiting concurrent sessions, and offline playback protected by licence-key encryption.
Contact
Let’s talk
Have an integration, a migration or a vendor proposal you don’t quite trust? Send me a few sentences and I will come back with a concrete proposal.