Senior Java Engineer — Hybrid in Denver

FusionAuth; Denver (CO); Hybrid; USD 140,000 - 180,000; Full time

Benefits offered by this job

Health insurance

401(k) plan

Generous PTO

Job summary

FusionAuth is hiring a Senior Software Engineer to build and extend our Java‑based platform, trusted by thousands of organizations and downloaded over 10 million times. You will design and ship complex features end to end, from technical design through release, applying OAuth 2.x, OpenID Connect and SAML protocols customers rely on.

This is a senior individual contributor role with real influence. You will review code for correctness and architectural fit, mentor engineers on debugging and

Qualifications

• 8-10 years of professional software development experience, with demonstrated ownership of complex features from design through release.
• Bachelor's degree in computer science, or demonstrable experience with a broad set of theoretical topics.
• Advanced Java skills, including threading, concurrency, and performance profiling.
• Strong object-oriented design and implementation skills.
• Solid understanding of the full web stack (HTTP, TCP/IP, REST).
• Real working knowledge of relational databases: query optimization, indexing, and schema design beyond ORM abstractions.
• Experience designing test approaches for complex features and writing end-to-end tests.
• Full-stack range including cloud infrastructure, backend services, and JavaScript on the front end.
• Comfortable using Claude Code or similar AI-assisted development tools.
• Headquarters in Denver metro; onsite 1-2 days/week preferred; travel to office quarterly if remote.

Responsibilities

• Feature development: Design and build complex features end-to-end, from technical design through release. Write high-quality, secure, well-tested production code.
• Technical design: Author Technical Design Documents (TDDs) and provide architecture recommendations.
• Code and design review: Review parts of the codebase for correctness, test quality, and architectural fit.
• Testing: Design test approaches for complex features, write end-to-end tests for critical paths.
• Debugging and troubleshooting: Diagnose and fix multithreaded and concurrency issues; participate in on-call rotation.
• Database: Optimize queries using indexes and constraints; understand ORM tradeoffs; NoSQL familiarity.
• Security: Apply least-privilege principles and understand encryption basics.
• AI-augmented development: Use LLMs in SDLC for review, documentation drafting, and refactoring.
• Technical roadmap: Identify tech debt and focus areas for the team.
• Cross-functional communication: Present designs to Product, DevSuccess, Support; translate constraints for non-engineering partners.
• Technical influence: Influence team decisions and lead knowledge-sharing on FusionAuth architecture.
• Customer engagement: Join customer calls to discuss integration questions.
• Documentation: Write clear documentation for features shipped.

Skills

Software development

Java

Concurrency

Web fundamentals

Testing

Full-stack

AI tooling

Education

Bachelor's degree or equivalent

Tools

Kubernetes

CI/CD

Claude Code

Job description

FusionAuth is hiring a Senior Software Engineer to build and extend our Java‑based platform, trusted by thousands of organizations and downloaded over 10 million times. You will design and ship complex features end to end, from technical design through release, applying OAuth 2.x, OpenID Connect and SAML protocols customers rely on.

This is a senior individual contributor role with real influence. You will review code for correctness and architectural fit, mentor engineers on debugging and