Java Backend Expert experienced in Frontend & Mobile | Full Stack Software Engineer
Full stack software engineer with 9+ years of experience building high-load, distributed, customer-facing systems with a background in nuclear physics. Primarily a Java expert (Java 21) with strong frontend (React JS, JS, TS, CSS, HTML) and mobile (React Native, Android/iOS) capabilities. Comfortable designing and implementing all layers of the stack—from databases and infrastructure to application layers—utilizing Java, Node.js with REST, and Kafka interfaces. Experienced in managing cloud-native environments on AWS, including data sources such as AWS Aurora, Redis, and S3 buckets. Skilled at translating complex technical challenges into clear solutions that bridge engineering and business needs.
Proficient with: Java 21, Spring Boot, React Native, React JS, JavaScript, TypeScript, Kafka, AWS (Aurora, S3), Terraform, CloudFormation, Microservices, LangChain, LangGraph, Datadog, Jenkins, Groovy, Docker, K6 load test, Node.js, FCM, Firebase, Data Lakehouse, Data JPA, MVC, Hibernate, JDBC, Oracle, PostgreSQL, Redis, Zookeeper, Apache Curator, Akka Actor Systems, Akka Streams.
Klarna is a global payments and BNPL company. My team runs over 30 Spring Boot Java microservices (Kafka/REST) handling the full Customer Communications lifecycle: orchestration, decisions, data enrichment, generation, scheduling, delivery, callbacks, and history.
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SMS (Business Critical / OTP) - Providers:
Twilio,
MessageBird
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Dynamic SMS Provider Switching:
Developed an automated system to monitor real-time
conversion and dynamically switch providers.
- Impact: Improved session conversion by 1%, resulting in a significant multi-million EUR revenue uplift across major markets.
- Reliability: Reduced provider failover from 30 mins to 1 min, cut SMS-related incidents by 60%, and ensured zero downtime during Black Friday 2024.
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Dynamic SMS Provider Switching:
Developed an automated system to monitor real-time
conversion and dynamically switch providers.
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Push Notifications (Payment Notifications)
- Provider:
FCM
- Push Infrastructure: Managed end-to-end infrastructure, including a Delivery Eligibility Check that reduced failed deliveries by over 50%.
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Braze Migration: Migrated marketing
pushes in-house by updating React Native Klarna App code
to send callbacks directly to Lakehouse.
- Impact: Achieved substantial monthly operational savings while tracking 30M+ monthly callbacks for 65M+ devices.
- Silent Push: Architected a separate channel for iOS silent pushes (Remote Device Login) and built the handler in React Native.
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Email (Business Critical / Transactional / Legal)
- Providers:
SendGrid,
SparkPost
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Rescheduling Logic: Engineered a
pre-send validation service to automatically reschedule
communications sent outside legal time windows.
- Impact: Ensured 100% legal compliance in the US by rescheduling 1.5M+ messages annually.
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Rescheduling Logic: Engineered a
pre-send validation service to automatically reschedule
communications sent outside legal time windows.
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Maintenance & Reliability
- Cloud Infrastructure: Managed and maintained high-availability Comms Platform resources on AWS, including Aurora PostgreSQL, Redis, and S3 buckets.
- Kafka Optimization: Identified and resolved a massive connection spike, reducing TCP traffic by 99.5% and significantly lowering regional Kafka costs.
- Performance Testing: Introduced k6 to the team, executing spike (600 req/s) and load tests to guarantee platform stability.
- CI/CD: Standardized Jenkins declarative pipelines, reducing deployment times by 20%.
Contracted via Gridfore LLC provides a platform for real-time big data analysis and decision making for banking and fintech.
- High-Load Engineering: Developed a distributed in-memory ETL data engine processing 500,000 records/sec using Akka Actor System and Akka Streams.
- Web Monitoring: Built the platform interface with React JS and Redux to provide real-time visibility into cluster states.
- Performance Engineering: Improved platform throughput by 20x through low-level profiling with YourKit and benchmarking with JMH.
This startup is changing the way companies recruit and how candidates interact with job applications by creating a simple, intuitive experience that caters to the needs of all involved parties.
- Designed a scalable recruitment platform using Golang and PostgreSQL on AWS.
- Developed frontend with React and Material UI (MUI) with Auth0 and Stripe integrations.
AT-Consulting provides custom software solutions and development and consulting expertise to customers.
- Maintained Oracle-based CRM systems for banking services using PL/SQL and JavaScript.
- Certification: Completed Module 1, covering LLM fundamentals, prompt engineering (zero-shot, chain-of-thought), and evaluation frameworks.
- AI Orchestration: Leveraged LangChain and LangGraph to design and implement agentic workflows and LLM-powered features within the Klarna ecosystem.
