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Backend Engineer – Java / Data Systems

Threecolts

Backend Engineer – Java / Data SystemsLocation:

Remote (Poland/EU) Contractor

Salary: $60,000

 

About Threecolts

Threecolts 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 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

  • 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
Published 19 August
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