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Salary: USD 190,000 - 230,000 / annual
FusionAuth is a fast-growing, venture-backed startup and leading provider of customer identity and access management (CIAM) software headquartered in Denver, Colorado. The company's mission is to make authentication and authorization simple and secure for every developer, helping businesses securely manage customer identities and access for some of the largest brands in the world.
This is a deeply hands-on Staff Software Engineer role where you solve the most complex technical problems directly in code. The role is not about sitting in reviews—technical design, mentorship, and leadership grow out of your credibility as a hands-on engineer. You will tackle demanding platform and feature initiatives within the FusionAuth core product, delivering resilient, secure, and thoroughly tested production code to resolve complex, open-ended technical challenges.
Key responsibilities include:
• Core Engineering & Ownership: Lead major end-to-end projects from scoping and estimation through technical design and general availability. Deliver production code that resolves complex technical challenges across self-hosted, on-premise, and dedicated cloud environments.
• 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.
• Quality & Review Standards: Elevate code and architectural review standards across the organization. Define and enforce standards for architectural integrity and testing quality, advancing test automation to satisfy enterprise-grade reliability.
• CIAM Protocol Expertise: Design advanced OAuth 2.x, OIDC, and SAML flows for enterprise deployments. Handle security edge cases, 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 authentication scenarios.
• Deployment & Compatibility: Factor FusionAuth's diverse deployment targets into every decision. Protect backward compatibility, API versioning, and upgrade paths across thousands of customer-managed environments. Apply security and compliance judgment (OWASP, data residency, encryption, GDPR) to how you build.
• Mentorship & Technical Influence: Mentor senior engineers toward Staff-level thinking and autonomy. Ramp junior engineers through pairing and review. Build consensus on hard technical calls across teams and communicate technical strategy to stakeholders with business context.
• AI Integration & Workflow Optimization: Evaluate and implement AI-driven solutions across the engineering team, embedding AI-augmented development and automated testing into everyday practices as FusionAuth modernizes its software development lifecycle.
The timing is critical: AI agents need their own authentication and authorization; passkeys are displacing passwords; delegated token exchange is rewriting how services trust each other. These problems are hard and consequential, and you will be one of the people solving them directly in code.
Work location: FusionAuth is headquartered in the Denver metro area and values in-person collaboration. The company strongly prefers candidates local to Denver who can be onsite 1-2 days per week. Candidates in other locations are welcome if willing to travel to the office 2-3 times per year.
REQUIREMENTS:
Required:
• Bachelor's degree in Computer Science or equivalent demonstrable technical depth
• 10+ years of professional software engineering with demonstrated staff-level technical competency
• Currently writes and ships production code; recent, active engineering is required
• Production-grade experience with OAuth 2.x, OIDC, and SAML, including ability to identify subtle misimplementations, guide protocol-correct designs, and handle federation and security edge cases
• Strong Java skills, including working understanding of the JVM (FusionAuth's core application is Java-based)
• Experience tuning PostgreSQL (or comparable relational database) at scale
• Experience designing or supporting software deployed across self-hosted or dedicated cloud environments, including backward compatibility and upgrade paths
• Uses AI development tools (e.g., Claude Code or Codex) as part of everyday workflow and has experience helping teams adopt AI-augmented development practices
• Pragmatism: appreciates first-principles thinking but knows when to stop theorizing and start building
Preferred:
• Direct experience building or working within a CIAM product or identity platform
• Familiarity with emerging identity protocols and standards (FIDO2/passkeys, DPoP, token binding, OAuth 2.x drafts)
• Experience diagnosing container and pod issues and reasoning about Kubernetes networking, storage, and resource limits in production
• Familiarity with compliance frameworks (SOC 2, FedRAMP, GDPR) and their impact on architectural decisions
• History of contributing to open-source identity or security projects, or publishing technical writing on identity topics
• Track record of ramping early-career engineers to productive, independent contributors
