Senior Software Engineer - Authentication Team

Role Overview

Senior Software Engineer – Customer Identity and Access Management (CIAM) team at Factorial.

Work on the full stack with a focus on backend development, primarily using Ruby on Rails and React.

Own a product domain area such as Authentication, Single Sign‑On, Multi‑Factor Authentication, Authorization, Permissions, or Auditing. Lead the foundation for both external and internal users to derive value from our platform.

• Design, develop, and ship features for the CIAM domain, ensuring high quality, security, and performance.
• Take ownership of large initiatives from conception to delivery, collaborating with product managers and designers.
• Engage in customer calls to understand pain points, gather requirements, and refine solutions.
• Review code daily and review pull requests, giving and receiving constructive feedback.
• Mentor junior engineers and share best practices in architecture, performance and engineering quality.
• Participate in RFCs and decision‑making processes to shape system architecture and product roadmap.

• Experience building B2B SaaS products with a focus on identity and access management.
• Strong backend development skills in Ruby on Rails; familiarity with React is a plus.
• Hands‑on experience with authentication, SSO (SAML/OIDC), MFA, and permissions models.
• Proactive, self‑starter who can work well under uncertainty while balancing strategy with execution.
• Excellent communication and collaboration skills in an English‑speaking, multicultural team environment.

Flexible office‑first policy: work onsite in Barcelona or Madrid several days a week, with remote work allowed for deep work or personal needs. Remote‑first tools and video‑conferencing support the entire hiring process.

• Private health insurance (Alan).
• Wellness program (Wellhub) – gym, pools and outdoor classes.
• Discounts with Cobee for savings.
• Language classes.
• In‑office breakfast and fruit.
• Pet friendly environment.
• Growth and learning opportunities in a rapidly scaling SaaS company.

A first conversation with a Talent Acquisition Partner to align expectations and review engineering rubrics and salary band.

A second conversation with the engineering manager to discuss team needs, technical fit and partnership.

A live engineering challenge with two senior engineers to demonstrate problem‑solving, communication, and technical execution.

Final coffee‑chat with the CTO to discuss culture, business vision and any remaining questions.

Factorial welcomes applicants from all backgrounds and strongly encourages people of diverse experiences and identities to apply. We are committed to equal opportunities and actively promote workplace inclusion of people with disabilities. Contact us for more information about inclusive recruitment processes.