Senior Backend Java Developer

Threecolts

Kraków, małopolskie
Stała
Pełny etat

6 dni temu

Senior Backend Engineer – Java / Data SystemsLocation: Remote (Poland/EU) ContractorSalary: $90,000About ThreecoltsThreecolts is a global software powerhouse for marketplace sellers and e-commerce brands. We help Amazon, Walmart, and multichannel operators scale through our suite of 24+ best-in-class SaaS tools — all available through our bundled solution, Seller 365. With a presence across 42 countries and a mission to support seller success, we're growing fast and hiring smarter.About the RoleWe’re looking for a Senior Backend Engineer to build and scale high-performance Java services that process massive data volumes, integrate with external systems, and run reliably in production. You’ll work on high-QPS systems, scraping pipelines, and cloud-native infrastructure.Responsibilities

Design, develop, and optimize backend services in Java (Spring Boot)
Build and maintain scalable, concurrent scraping systems (Selenium / Playwright)
Implement caching, async messaging, and streaming using Redis and Kafka
Optimize PostgreSQL queries for high-throughput workloads
Parse and process data from multiple sources and file formats
Deploy, monitor, and maintain applications on Kubernetes and AWS (EC2, EKS, RDS, S3)
Tune JVM performance and ensure system scalability
Set up monitoring, metrics, and alerts using Prometheus and Grafana
Troubleshoot and improve system reliability and infrastructure

Requirements

7+ years experience
Strong Java (Spring Boot) backend development
PostgreSQL: query optimization, high-throughput environments
Redis & Kafka for caching and async messaging
Build concurrent scraping systems (Selenium / Playwright)
Multithreading, parallel/multiprocessing, async comms
Parse and process multiple file types (HTML, PDF, CSV, XLS, DOC, Parquet, etc.)
Deploy & manage apps in Kubernetes (stateless & stateful)
AWS: EC2, EKS, RDS, S3
JVM tuning & performance optimization
Large-scale data transformation/processing
Monitoring & alerting with Prometheus and Grafana
Kubernetes infrastructure troubleshooting

Nice to Have

Node.js, TypeScript, Python
Scraping anti-bot strategies
AI/LLM-based automation & data processing

Threecolts

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