Principal Software Engineer

About the role

FusionAuth 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 FusionAuth to the next level.

Job Summary

FusionAuth is hiring a Principal Engineer to serve as a senior technical authority on customer identity. This person will be a key contributor to the architectural direction of the FusionAuth platform, carry deep protocol expertise (OAuth 2.x, OpenID Connect, SCIM, SAML), and guide enterprise customers on how FusionAuth fits into their identity architectures. The role reports directly to the SVP of Engineering & Technology.

Responsibilities

• Development: Write, review, and own high-quality, secure production code on the FusionAuth core application. This is a hands-on technical leadership role, not a design-only position.
• Architecture: Provide leadership for the platform’s architectural evolution. Draft and review Technical Design Documents (TDDs), ensuring designs meet FusionAuth’s standards for scalability, security, and quality before implementation begins.
• CIAM Protocol Expertise: Serve as a go-to expert on OAuth 2.x, OIDC, SCIM, and SAML. Guide protocol-correct implementation across the product. Answer hard protocol questions from engineering, Support, Solutions Engineering, and customers.
• Customer Engagement: Engage directly with enterprise prospects and customers on architectural and integration design decisions. Translate complex CIAM concepts clearly for both technical and semi-technical audiences.
• Industry & Technology Leadership: Track where the identity industry is heading: passkeys/FIDO2, device authorization, DPoP, token binding, emerging OAuth and OIDC drafts, and the rapidly evolving intersection of AI and identity (agent authentication, scoped credential issuance, authorization for AI-driven workflows). Monitor broader technology trends and bring well-reasoned perspectives on what FusionAuth should build, adopt, or avoid. Partner with Product Management to translate these insights into roadmap decisions.
• Industry Representation: Represent FusionAuth at industry conferences, working groups, and community events. Build FusionAuth’s technical credibility in the identity and security ecosystem.
• Deployment & Compatibility: Factor FusionAuth’s diverse deployment targets into every architectural and feature decision. Ensure backward compatibility, API versioning integrity, upgrade paths, and sound schema migration strategy for a product running across thousands of customer-managed environments.
• Team Development: Mentor engineers across the team. Raise CIAM knowledge through code reviews, design discussions, architectural sessions, and informal knowledge sharing.
• Cross-Functional Collaboration: Work closely with Product Management, Solutions Engineering, and Customer Success on complex customer situations, roadmap decisions, and new feature design.

Qualifications

• Education: Bachelor’s degree in Computer Science or equivalent demonstrable technical depth.
• CIAM Protocol Depth: Production-grade expertise in OAuth 2.x, OIDC, SCIM, and SAML. The ability to identify subtle misimplementations, guide protocol-correct designs, and explain nuanced tradeoffs.
• Experience: 12+ years of professional software engineering, including 5+ years focused on identity, authentication, or security, with meaningful time at the principal, staff, or architect level.
• Hands-On Development: Proven track record of shipping code alongside architectural responsibilities. Not an architect who stopped coding.
• Distributed Systems: Experience with enterprise-grade, highly available, high-performance distributed systems.
• Deployment Architecture: Experience designing or supporting software deployed across self-hosted, on-premise, or dedicated cloud environments. Understanding of backward compatibility, upgrade paths, and performance tuning across customer-managed infrastructure.
• Customer-Facing Experience: Demonstrated ability to engage directly with enterprise customers and prospects on technical design and architecture.
• Design Review: Experience reviewing and approving technical designs in a formal or informal architecture review capacity.
• Emerging Standards: Familiarity with emerging identity protocols and standards (FIDO2/passkeys, DPoP, token binding, OAuth 2.x drafts, etc.).
• AI-Native Development Practices: Willingness to adopt and use AI-assisted development tools (e.g., Claude Code, GitHub Copilot) as part of everyday workflow.
• Pragmatism: Appreciates first-principles thinking, but knows when to stop theorizing and start building.
• Work Location: FusionAuth is headquartered in Denver, Colorado, and we value the creative energy and collaboration that comes from working together in person. We strongly prefer candidates based in the Denver metro area and have a hybrid working arrangement for local employees. We are open to candidates in other locations who are willing to travel to our Denver headquarters approximately once per quarter.

Compensation

$225k–$270k expected base salary range*

*Pursuant to various state laws, we must display the pay range for this job. Since we are willing to hire within a broad spectrum of qualifications, this range is broad. The expected base salary may be adjusted based on individual qualifications, role, level and location.

Onsite Perks & Campus Benefits

• Newly upgraded amenity spaces including a sleek tenant lounge and café with booth seating and collaborative workspaces.
• Access to a fitness studio, showers, lockers, and secure bike storage.
• Regularly stocked in-suite kitchen with a variety of snacks and beverages to keep you fueled throughout the day.
• Onsite café offering chef-driven menus with fresh, locally sourced, organic, and non-GMO options to suit diverse dietary needs. Easy ordering via app.
• 3-acres of green space, including communal parks and picnic areas, connected to miles of jogging, biking, and recreation trails.
• Yoga in the circle and wellness programs to enhance work-life balance.
• Dedicated outdoor workspaces and patio gathering areas.
• Ambient on-site parking, easy freeway access, and high-speed fiber internet.
• Sustainability-minded campus and community initiatives, including support for regenerative agriculture programs.

Benefits

• Comprehensive health insurance including medical, dental, and vision coverage, with the company covering the majority of your medical premiums to keep your costs low- Fully employer-paid High Deductible Health Plan (HDHP) option paired with a Health Savings Account (HSA), including employer contributions
• Basic life insurance and short- and long-term disability coverage fully paid by the company for essential financial protection
• Voluntary life insurance options to provide additional financial protection for you and your loved ones
• Healthcare and Dependent Care Flexible Spending Accounts (FSAs) to save pre-tax dollars on eligible expenses
• 401(k) plan with company match to help you save for retirement
• Generous paid time off (PTO) plus paid company holidays to support work-life balance
• Employee Assistance Program (EAP) offering confidential counseling and support services
• Professional growth and development opportunities to boost your career journey
• Eligibility for performance-based bonuses or variable compensation tied to individual, team, or company results