Senior Full‑Stack Developer (RoR/React)

Kernelics - is an international company with development centers in Poland and Georgia. We are passionate about gathering the best IT specialists and building teams for tech startups all over the world. 
If you are also keen on start-ups and innovative projects, if it is important for you to work in a team of professionals and help customers realize their ideas that make this world more convenient, brighter and more technology oriented - Kernelics is definitely your place.

What are you going to deal with?
Project: WiddyUP is a fundraising platform where kids create and safely share awesome videos with family and friends in a unique way to raise money.

Hiring process: 

🔹 HR interview + + tech questions for ROR + React(50 - 60min, Kernelics)

🔹 Internal tech ROR + React (optional)

🔹 Call with team lead - general questions

What are you expected to do?

🔹 Understand the existing Rails application and its production workflows.

🔹 Modernize Rails incrementally into a clean API-first backend; no big-bang rewrite.

🔹 Build new React web features and APIs reusable by the React Native/Expo app.

🔹 Remove or replace legacy code and upgrade outdated dependencies safely.

🔹 Work with PostgreSQL, Sidekiq/Redis, Stripe, AWS, and Elastic Beanstalk.

🔹 Add tests, review AI-generated code, and ship small, reliable releases.

What do we expect from you?

🔹 5+ years of software engineering experience with strong Ruby on Rails and React skills.

🔹 Production experience modernizing or upgrading a legacy Rails application.

🔹 Strong REST API, PostgreSQL, background jobs, authentication, and authorization knowledge.

🔹 Experience with Stripe, AWS, automated testing, CI/CD, and production debugging.

🔹 Able to work independently with a technical lead and communicate clearly in English.

Bonus:

🔹React Native/Expo.

🔹 Rails/Ruby upgrades and migration from ERB, jQuery, or Webpack to React.

🔹 User-generated media, video, fundraising, or K-12 products.

🔹 Practical use of Claude Code, Cursor, Copilot, Codex, or similar tools.

What can we offer? 
🔹 Taking care of your health - fixed benefit health care coverage.
🔹 Supporting your active lifestyle - sports activities with 50% coverage up to the fixed amount. 
🔹 Treating you not only as a team member but as a personality as well - do not even hope that we'll skip your birthday or other significant events in your life, such as a wedding and birth of a child.
🔹 Supporting your professional and personal development.
🔹 Maintaining work-life balance - you can work from anywhere you wish, flexible working hours within working hours of the project. 
🔹 Working among your friends - refer our open vacancies to your friends and receive a decent referral bonus. 
🔹 Enjoying corporate life that is full of bright emotions and impressions - we hold regular online and offline events and activities.