Software Engineer; Hybrid, Denver Metro

Job Title:

Staff Software Engineer

Location:

Hybrid, Denver Metro Preferred

About Fusion Auth

Fusion Auth is a fast-growing startup and leading provider of customer identity and access management (CIAM) software headquartered in Denver, Colorado. Our mission is to make authentication and authorization simple and secure for every developer. Our product helps businesses securely manage customer identities and access, ensuring a seamless and safe user experience for some of the largest brands in the world.

We are committed to delivering exceptional value and satisfaction to our clients through top-notch service and support. With a great team and strong investors, we are expanding our team to help accelerate our growth and take Fusion Auth to the next level.

Fusion Auth is hiring a Staff Software Engineer to operate as a senior hands-on engineer. This is a deeply hands-on technical role: you solve the most complex problems, and the rest of the job (review, technical design, mentorship) grows out of that credibility rather than sitting apart from it.

The timing matters. AI agents need their own authentication and authorization. Passkeys are displacing passwords. Delegated token exchange is rewriting how services trust each other. Fusion Auth ships into self-hosted, on-premise, and dedicated cloud environments across thousands of customer-managed deployments, so every decision here carries real weight. These problems are hard and consequential, and as a Staff engineer you will be one of the people solving them directly in the code, not just reviewing them after the fact.

You will also carry protocol expertise (OAuth 2.x, OpenID Connect, SAML, JWT) and engage directly with enterprise customers on implementation guidance and integration architecture. You drive impact by pairing sound technical judgment with cross-functional consensus-building - guiding senior engineers toward staff-level execution, aligning teams around complex architectural decisions, and sharing expertise through designs, code reviews, and technical discussions.

• Core Engineering & Ownership:
  Tackle the most demanding platform and feature initiatives within the Fusion Auth core product. Deliver resilient, secure, and thoroughly tested production code to resolve complex, open-ended technical challenges. Lead major end-to-end projects, collaborating with peers to manage everything from scoping and estimation to technical design and general availability.
• Technical Design:
  Write Technical Design Documents (TDDs) for key initiatives, advocating clear technical directions while remaining receptive to feedback. Provide strategic guidance to senior engineers on architectural plans to ensure alignment with Fusion Auth's standards for quality, security, reliability and scalability.
• Quality & Review Standards:
  Elevate code and architectural review standards across the organization, integrating continuous learnings into the AI software development lifecycle. Define and enforce standards for architectural integrity, and testing quality, while advancing test automation and coverage to satisfy enterprise-grade reliability requirements.
• CIAM protocol expertise:
  Design advanced OAuth 2.x, OIDC, and SAML flows for enterprise deployments. Handle security edge cases and federation patterns, and guide protocol-correct implementation across the product.
• Customer engagement:
  Engage directly with enterprise customers and prospects on implementation guidance, integration architecture, and troubleshooting complex auth scenarios.
• Deployment and compatibility:
  Factor Fusion Auth's diverse deployment targets into every decision. Protect backward compatibility, API versioning, and upgrade paths across thousands of customer-managed environments, and apply security and compliance judgment (OWASP, data residency, encryption, audit requirements like GDPR) to how you build.
• Mentorship and technical influence:
  Mentor senior engineers toward Staff-level thinking and autonomy, and ramp junior engineers through pairing and review. Build consensus on hard technical calls across teams, and communicate technical strategy to stakeholders with business context, representing engineering with Product, Sales Engineering, and Support.
• AI Integration & Workflow Optimization:
  Evaluate and implement AI-driven solutions and organizational context across the engineering team, embedding AI-augmented development and automated testing into everyday practices as Fusion Auth modernizes its software development…