Senior Software Engineer - Ruby on Rails (m/f/x)
Uses AI coding assistants as a pragmatic pair-programmer but explicitly forbids 'vibe coding'; AI is used for boilerplate, tests, and refactoring while maintaining strict architectural oversight.
About the Role
Senior Software Engineer (Ruby on Rails) building and scaling backend systems for a European fintech focused on brokerage and robo-advisory. The role is fully remote and emphasizes high-quality, secure, well-tested code, distributed systems expertise, and pragmatic use of AI coding assistants to increase productivity.
Job Description
Role
Whitebox is hiring a Senior Software Engineer (Ruby on Rails) to architect, build, and scale core financial systems for brokerage operations and robo-advisory platforms. The position is full-time and fully remote, and expects an engineer who values craftsmanship, secure design, distributed-systems correctness, and strong remote collaboration.
Key Responsibilities
- Design and maintain reliable backend services powering brokerage and robo-trading engines.
- Implement complex financial logic and business rules using Ruby on Rails.
- Champion Test-Driven Development (TDD) and Behavior-Driven Development (BDD) to ensure reliability.
- Manage complex state and ensure data integrity across distributed systems and transactions.
- Containerize applications and maintain local and deployment workflows using Docker.
- Collaborate asynchronously and synchronously in a fully remote Agile environment.
- Integrate AI coding assistants pragmatically for boilerplate, test generation, and refactoring while maintaining strict architectural oversight.
Requirements
- Extensive, production-level experience with Ruby on Rails.
- Strong security mindset with experience in secure coding practices, data encryption, OWASP principles, and secure API design.
- Deep commitment to TDD and BDD and proven testing discipline.
- Strong understanding of distributed systems transactions, state management, and data consistency.
- Experience working in distributed, Agile teams with excellent written and verbal communication.
- Solid experience with Docker and containerized environments.
- Domain knowledge of financial markets, brokerage mechanics, and automated/robo-trading concepts.
- Proven experience using AI tools as productivity multipliers in development and testing workflows.
Nice to Have
- Java experience for interfacing with or transitioning high-performance services.
- Familiarity with Rust for low-latency components.
- Knowledge of European financial regulations (e.g., MiFID II).
- Experience with the FIX protocol for order routing.
- Kubernetes (K8s) experience.
- Familiarity with CI/CD pipelines.
- Experience with Spec-Driven Development tools.
Benefits and Perks
- 100% remote work.
- Thirty days of paid vacation.
- Attractive remuneration package.
- Free choice of hardware.
- Individual learning budget and personal career development.
- Free access to Whitebox wealth management.
- Virtual get-togethers and on-site team activities.
- Weekly manager one-on-ones, flat hierarchies, open-door mentality.
- Regular knowledge-sharing sessions and communities of practice.
Onboarding: First Week / Month / Quarter
- First week: introductions, one-on-ones, and organizational context.
- First month: orientation in the codebase, design decisions, and system overview.
- First quarter: full integration into the team, contributing to projects, and participating in engineering strategy and principles.
Work Environment
- Permanent, full-time (40h/wk).
- Fully remote position within a distributed engineering team of 20+.
- Role reports to Eneko Taberna.