Sr Software Engineer, Applications

ABOUT THE TEAM

The Auth team owns the systems that decide who can do what across Basis: authentication, identity, and fine-grained authorization for a platform built on complex agency and org hierarchies. We're an enabling team: every product team at Basis depends on the primitives, policies, and infrastructure we build and own. That now includes authorization for AI agents operating alongside human users, not just human users alone.

WHAT YOU'LL DO

• Extend our identity layer in Auth0: authentication flows, token issuance, identity federation.
• Build and maintain our ReBAC authorization model in OpenFGA, the system every authorization decision on the platform runs through.
• Own the details of OAuth 2.0 and OIDC in our stack: token flows, JWKS validation, scopes, audience restrictions.
• Define how AI agents authenticate and receive scoped permissions, so non-human actors operate under the same authorization model as people.
• Drive technical projects that cut across multiple teams and systems, from design through production.
• Set technical direction and quality standards for the team and review the work that ships against them.
• Support and mentor other engineers through code review, design discussions, and day-to-day collaboration.

WHAT YOU BRING TO THE TABLE

• 5+ years of professional software engineering experience.
• Deep, hands-on knowledge of OAuth 2.0 and OpenID.
• Experience with ReBAC systems (OpenFGA, Zanzibar, SpiceDB): modeling schemas, writing and testing tuple-based policies, and reasoning about permission evaluation performance.
• Experience with Auth0 or a comparable identity provider (Okta, Azure AD, Keycloak).
• Strong backend skills in Java, Ruby, or Python, with frameworks such as Spring Boot, Rails, or Django.
• Regular use of AI coding tools (Claude Code, Cursor, Codex) for code generation, debugging, and exploring unfamiliar code, and the judgment to own and vet what they produce.
• A collaborative approach to design and decision-making, and a commitment to building an inclusive team.

BONUS POINTS

• Experience building or scaling auth systems for a platform with complex organizational hierarchies (agencies, multi-tenant SaaS, etc.).
• Familiarity with policy-as-code or attribute-based access control (ABAC).
• Background in ad tech or programmatic advertising.
• Contributions to open-source identity or authorization projects.

OUR TECH STACK

• Languages: Ruby, JavaScript, Java
• Auth & Identity: Auth0, OpenFGA
• Infrastructure: AWS, Docker, Kubernetes
• Data: PostgreSQL, Redis
• Frameworks & Tools: Spring Boot, Rails, Node.js, React, RabbitMQ, Sidekiq