Senior Fullstack Engineer (BE)

As a Senior Fullstack Engineer, you will work on our high-load trading platform that connects to 15+ exchanges and powers manual and automated strategies with DCA, Grid, and Signal bots. You’ll build and own complex features end-to-end on a modern stack.

Responsibilities:

• Develop and maintain a modular, scalable SaaS platform using Ruby on Rails.
• Implement new features and improve existing ones in close collaboration with product and design teams.
• Take ownership of your code in production: monitoring, alerting, and ongoing support.
• Address high-load and security-related challenges in backend and full-stack solutions.
• Mentor and support the growth of other engineers on the team.
• Integrate external API services and ensure their secure and stable operation.
• Ensure code quality and performance through early involvement in QA and testing workflows (shift-left approach).
• Contribute to quality through automated tests, code reviews, and proactive refactoring.
• Collaborate closely with cross-functional teams including DevOps and QA.
• Stay up to date with best practices in backend architecture, performance, and security.

Requirements:

• 4+ years of experience in Ruby on Rails backend development.
• Proven experience with React and TypeScript.
• 6+ years of proven full-stack commercial development experience.
• Strong knowledge of PostgreSQL and relational modeling at scale: large tables, replication, partitioning, multi‑DB per app, query planning and indexing.
• Hands-on approach to software engineering best practices: TDD, refactoring, code review, and system design.
• Familiarity with AWS services (e.g., Lambda, DynamoDB).
• Hands-on experience with key-value stores (Redis, Memcached, etc.).
• Experience integrating third-party APIs and services.
• Ability to design and build scalable, secure, and maintainable features.
• Strong communication skills and collaborative mindset.
• Proficiency in English (B2 level or higher, spoken & written).
• Commitment to participating in quality assurance workflows and a strong understanding of the “shift-left” approach.

Nice to Have:

• Basic experience with Go and interest in growing your skills in it.
• Familiarity with Kubernetes and microservice orchestration.
• Knowledge of Kafka, RabbitMQ or similar messaging/streaming systems.
• Experience tackling high-load scenarios and optimizing performance bottlenecks.
• Hands-on experience with observability tools like Grafana, CloudWatch, etc.

Why Join 3Commas.io?

Impact at Scale‍

Drive product innovation for a platform used by millions of traders and developers worldwide.

Strategic Influence‍

Shape the product roadmap and user experience alongside executive leadership.

Culture of Growth‍

Join a passionate, talented team where ideas are valued, and careers are accelerated.

Global & Remote‍

Work flexibly from Barcelona, Tallinn, Cyprus — or remotely, in sync with our distributed product and tech teams.