Principal Software Engineer (Ruby Expert)

Sigma Software; Warszawa; On-site; PLN 250,000 - 350,000; Full time

Job summary

Sigma Software in Warszawa seeks a Principal Software Engineer with deep Ruby expertise to lead the technical direction of our platform and drive scalable systems. You will architect high-performance solutions, mentor engineers, and collaborate across teams to deliver robust features while maintaining code quality and engineering excellence.

The role demands hands-on coding balanced with strategic thinking, cloud familiarity, and a passion for cutting-edge technologies to keep us ahead in a

Qualifications

• 8–10+ years of software development experience with leadership.
• Expert-level Ruby and Rails expertise.
• Bachelor's degree in CS/SE or equivalent.
• Proficient in PostgreSQL/MySQL and Git.
• Strong knowledge of software design patterns and testing.
• Experience with TDD and automated testing frameworks.
• Experience with Agile methodologies and distributed systems.
• Ability to mentor junior developers and lead teams.

Responsibilities

• Architect and implement scalable, high‑performance Ruby/Rails solutions.
• Lead the design and development of new features and products with strong coding standards.
• Collaborate with cross‑functional teams to define technical strategies.
• Mentor and guide junior developers, conduct code reviews and provide feedback.
• Optimize existing systems for performance and scalability; evolve tech stack.
• Participate in technical decision‑making and future engineering direction.
• Stay up‑to‑date with emerging technologies and industry trends.

Skills

Ruby

Ruby on Rails

Leadership

TDD

Cloud platforms

Databases

Git

Agile methodologies

Education

Bachelor's degree in Computer Science, Software Engineering, or related field

Tools

Git

PostgreSQL

MySQL

AWS

Job description

Principal Software Engineer (Ruby Expert)

• Full-time

We are looking for an experienced Principal Software Engineer with deep expertise in Ruby to lead the technical direction of our platform and drive the development of complex, scalable, and high-performance systems.

In this role, you will define architectural strategy, make key engineering decisions, mentor the team, and ensure the highest standards of code quality and engineering excellence.

The ideal candidate combines strong hands-on skills with strategic thinking, product awareness, and a passion for building robust, efficient, and future-proof solutions.

• Architect and implement scalable, high-performance software solutions using Ruby and Ruby on Rails
• Lead the design and development of new features and products, ensuring code quality and best practices
• Collaborate with cross-functional teams to define and implement technical strategies
• Mentor and guide junior developers, fostering a culture of continuous learning and improvement
• Conduct code reviews and provide constructive feedback to team members
• Optimize existing systems for improved performance and scalability
• Contribute to the evolution of our technology stack and development processes
• Participate in technical decision-making and help set the direction for our engineering efforts
• Stay up-to-date with emerging technologies and industry trends, recommending innovations when appropriate
• Troubleshoot and resolve complex technical issues in production environments
• Expert-level proficiency in Ruby and strong knowledge of Ruby on Rails framework
• 8-10+ years of software development experience, with a proven track record of leading complex projects
• Bachelor's degree in Computer Science, Software Engineering, or related field (or equivalent experience)
• Proficiency in database systems (e.g., PostgreSQL, MySQL) and version control systems (e.g., Git)
• Deep understanding of software design patterns, principles, and best practices
• Experience with test-driven development (TDD) and automated testing frameworks
• Knowledge of scalable and distributed systems architecture
• Familiarity with cloud computing platforms (e.g., AWS, Azure, GCP)
• Strong problem-solving skills and ability to architect complex software solutions
• Excellent communication and leadership abilities, with experience mentoring junior developers
• Experience working with Agile methodologies
• Ability to balance technical leadership with hands-on coding
• Passion for staying current with emerging technologies and industry trends