Senior Ruby on Rails Developer (6‑Month Contract)

Sii Ukraine is a subsidiary of Sii Poland — the leader in IT, engineering, and consultancy services with over 7500 IT experts in Poland and more than 250 prestigious customers. We are looking for ambitious and top-quality professionals to join our project teams.

As a Senior Ruby on Rails Developer, you will join the team contributing directly to a large‑scale Case Management system used by enterprise clients across banking and insurance sectors. This is an exciting opportunity to work on a high‑impact platform that demands exceptional performance, security, and reliability.

Your tasks:

• Analyzing and participating in review sessions – assessing development needs, reviewing architectural approaches, and taking part in requirement analysis, design discussions, and SCRUM meetings
• Creating and maintaining project documentation, validating technical solutions, and ensuring architectural consistency before deployment
• Designing, developing, and optimizing Ruby on Rails applications, including advanced data processing, performance tuning, workflow optimization, and configuration of key platform components
• Working with PostgreSQL (complex queries, schema design, performance tuning), Redis (caching and in‑memory strategies), and background job processing (e.g., Sidekiq)
• Building scalable features, advanced filtering mechanisms, and solutions handling large datasets and enterprise‑level workflows
• Ensuring compliance with internal development standards and identifying automation opportunities, including the use of AI‑augmented development tools (GitHub Copilot, ChatGPT, Claude)
• Supporting testing and deployment activities while collaborating closely with cross‑functional team members across Europe

Requirements:

• Minimum 8 years of experience working with Ruby and Ruby on Rails, with proven ability to design and maintain complex applications

• Strong experience with:

  1. PostgreSQL (advanced database design and performance optimization)
  2. Redis (caching strategies and in‑memory data management)
  3. Scheduled jobs and asynchronous processing (Sidekiq or similar)
  4. Advanced search/filtering for complex enterprise datasets

• Ability to handle complex architectural challenges and optimize high‑load platforms
• Demonstrated use of AI tools (GitHub Copilot, ChatGPT, Claude) in daily development workflow
• Methodical, analytical, and structured approach to problem‑solving
• Excellent communication skills in English
• Tax residence in Ukraine is required

Preferred Qualifications:

• Understanding of the SMTP protocol and email delivery pipelines
• Experience deploying or managing cloud infrastructure in Azure, AWS, or Private Cloud environments