Backend Developers in Berlin

Company in the industrial sector

Projects completed during retraining

• Rebuilt the company website from WordPress using a modern stack with Astro and TypeScript, deployed on Vercel (live at sybarium.vercel.app); replaced the legacy CMS with a faster, maintainable system.
• Reduced page load time by ~80% (from 5 s to under 1 s) through optimization, caching, and asset optimization.
• Developed n8n automation workflows that integrate several REST APIs and internal systems, saving more than 3 hours of manual work per week.

• Coach international tech professionals through career transitions, helping high achievers move from reactive decision-making to clarity-driven career and life choices.
• Combined software engineering and consulting background with coaching expertise to address challenges specific to the tech industry, including career stagnation, imposter syndrome, and uncertainty around AI's impact on the field.
• Some of my client's measurable outcomes include landing multiple concurrent interview processes after a multi-year career gap, launching independent product ventures, securing technical roles that improved both financial stability and job performance, transitioning into non-tech careers.
• ~200 hours of coaching sessions. Guided clients through 1:1 and group coaching engagements, ranging from single sessions to year-long partnerships, focused on sustainable, values-aligned career growth.

Built and scaled a high-performance enterprise API for real-time address validation and data quality with sub-second latency and 99.9 % availability.

Designed and integrated the solution into e-commerce, checkout, and logistics processes of leading European companies. Reduced delivery errors and shipping costs through automated data correction and precise data validation.

End-to-end responsibility for product strategy, technical architecture, software development, enterprise customers, operations, and GDPR-compliant data processing. Combined AI-native engineering workflows, Python, SQL, API integration, data quality, and workflow automation.

Java 21 · Spring Boot 3 · Keycloak · PostgreSQL · Docker · Nginx · GitHub Actions · DigitalOcean · React 18 · TypeScript · Plasmo

• Architected and shipped a production-ready Job Application Tracker end-to-end: REST API with 5-stage workflow, pagination, sorting, and dynamic filtering — full ownership from design to live cloud deployment on DigitalOcean.
• Implemented production-grade identity management: OAuth 2.0 / OpenID Connect / JWT / RBAC via Keycloak, applying Hexagonal Architecture and DDD principles.
• Built automated CI/CD pipeline (GitHub Actions); containerised with Docker; Nginx reverse proxy with path-based routing and SSL termination.
• Developed a Chrome Extension (Plasmo framework, Manifest V3) that auto-fills job applications directly from LinkedIn into the tracker — demonstrates full product thinking across backend API and browser client.

• Lecturer for the GenAI Track at Master School Institute of Technology
• Development of a full-stack AI application (React + Python/FastAPI) for automated supplier product imports with intelligent column and category classification (4-layer hierarchy), including human-in-the-loop validation

• Client: Terex Corporation

• Opt-in RAG extension over tenant-owned data sources (SharePoint, Confluence) on existing multi-tenant enterprise AI platform
• Architecture: ADRs, solution evaluations, permission strategy, cost modeling
• End-to-end SharePoint and Confluence connectors: OAuth consent flows, token refresh, metadata sync, search integration
• Permission resolution: ACL indexing at ingestion and query-time verification (document-level security)
• Elasticsearch hybrid search (semantic + keyword) with RRF scoring
• RAG chat with context injection and source citations
• Stack: Elastic Cloud, Elasticsearch, Docker, Northflank, Next.js, React, TypeScript, Prisma, Microsoft Graph API, Atlassian REST API, OAuth 2.0

• Subject matter expert for the client on modeling and developing Camunda BPMN 2.0
• Development of new features and APIs, and coordination of tasks
• Design and development of RESTful APIs with Swagger (code first)
• Creation of target designs, high-level concepts, and requirement specifications
• Analysis and evaluation of alternative solution approaches
• Integration of external IT systems (ANUBIS, SES, ZPS) via Google GCP Pub/Sub and RESTful web services
• Pair programming, code reviews, and collaboration with API product owners
• Consulting on transforming legacy BPMN workflows and configuring Camunda BPM
• BPMN and DMN modeling and implementation in short iterations
• Operational support, bug fixing, and knowledge documentation
• Use of TDD, static code analysis with SonarQube, and integration tests
• Automation of test cases in Java and analysis of stack traces/logs on GCP-PROD
• Identification and execution of test data and documentation of test results

Led backend engineering across core domains (main backend, notifications, medical knowledge base, results processing), owning delivery quality, team growth, and engineering standards.

Signature Outcomes

Shipped a flexible, no-code membership platform (pricing, packages, duration), enabling commercial changes without engineering involvement and keeping membership tiers coherent over time.

Built a high-impact backend team through mentorship, coaching engineers into independent contributors and establishing onboarding documentation that enabled fast ramp-up.

Scaled the team from 2 → 5 engineers while maintaining delivery cadence and code quality; owned hiring pipelines and onboarding.

Partnered closely with Product during design to assess feasibility, sequence work, and make pragmatic trade-offs between speed, tech debt, and long-term maintainability.

Institutionalized testing and simplicity as defaults, enforcing high test coverage and a “simple-first” architecture approach.

Tech & Practices

Stack: Node.js (TypeScript), Express, PostgreSQL; microservices (Node & Go); event-driven async jobs.

Practices: Testing as a release gate, lightweight design reviews, iterative delivery, documentation-driven onboarding.

Compliance & Security: Led implementation of Privacy Officer recommendations (GDPR and German healthcare regulations).

• Providing freelance software engineering and AI orchestration services for an early-stage startup.
• Designing and coordinating autonomous AI systems capable of executing complex, multi- step workflows.
• Developing customer-facing pilots and proof-of-concept solutions.
• Participating in meetings with customers and investors to support product development and business discussions.

• Developed APIs for advanced credit default swap analytics supporting both MongoDB and file-based workflows

• Heycar is a leading automotive platform redefining the used car market through intelligent data pipelines, multi-tenant services, and dealer-focused tooling. I led initiatives across backend architecture, data ingestion, and identity management to enhance scalability, reliability, and developer productivity.
• Ingestion Platform: Designed a unified ingestion platform with YAML-based configuration, enabling new dealer data pipelines to be onboarded without code changes, cutting setup time from ~2 months to 2-3 days and improving scalability by 40%.
• Keycloak Leadership: Acted as the company's Keycloak expert, scaling it for multi-tenant identity management and extending functionality with custom plugins and delegated admin APIs.
• Back-Office Tooling: Developed a back-office application integrated with Salesforce, enabling dealers to manage inventory, convert leads, and handle support requests in real time.
• Multi-Tenant Migration: Collaborated across backend teams to migrate Heycar's core services into a unified multi-tenant cluster, ensuring high availability.
• Frontend CI Optimization: Optimized monorepo delivery by implementing CircleCI dynamic config with NX, deploying only affected UI projects and drastically cutting build times.
• Observability & Mentorship: Enhanced monitoring and release reliability while mentoring backend engineers and improving code review standards.

• Developed and maintained Kotlin-based microservices with Kafka event streaming, applying Hexagonal Architecture and Domain-Driven Design in production environments.
• Contributed to the Bring-Your-Salary feature, enabling seamless onboarding of new salary accounts and improving customer experience.
• Built and integrated services for the FPAD VOP platform, supporting secure and scalable partner integrations.
• Investigated and resolved production incidents through root cause analysis (RCA), implementing fixes that improved service stability and reliability.

• Built a scalable data platform processing millions of structured records daily from multiple sources, enabling near real-time analytics, dashboards, and secure report exports.
• Supported business decision-making by reducing latency in insights and ensuring data reliability.
• Designed and deployed high-throughput Kafka ingestion pipelines, reliably processing millions of records daily for enterprise analytics.
• Built a Redis-based distributed self-healing task system, reducing manual intervention by ~90% and improving overall platform reliability.
• Improved database write performance, increasing ingestion throughput by ~40% and enabling near real-time data availability.
• Developed high-performance RESTful APIs for multi-dimensional analytics and TopN statistics, supporting enterprise teams in identifying key trends and anomalies.
• Optimized queries with caching, materialized views, and partitioned tables, reducing latency under heavy load by ~80%.
• Integrated application-layer Role-Based Access Control (RBAC) to enforce fine-grained data permissions, ensuring secure API access and compliance.
• Improved Jenkins + AWS EKS CI/CD pipelines for zero-downtime deployments and automated rollback, reducing deployment failures by ~90%.