Principal Software Engineer

What You Will Make an Impact On

• Lead the architecture and implementation of major initiatives in our platform
• Make architectural decisions counterfactually - considering several plausible approaches, surfacing the trade-offs, and choosing the best path rather than defaulting to a generic template
• Provide technical leadership across all phases of large-scale engineering work, from scoping and design through implementation, code review, rollout and maintenance
• Work cross-functionally with the Director of Engineering, fellow principal engineers, infrastructure engineers, product managers, DevOps, and QA to drive complex decisions on product direction and process improvements
• Design and implement user-facing and backend features across the entire platform
• Produce high-quality code that is well designed, thoroughly tested, and passes peer review
• Mentor engineers across the team, raise the architectural literacy of the group, and actively contribute to brainstorming and design discussions
• Champion thoughtful use of AI and agents in our SDLC, helping the team amplify their work

What You Bring to the Team

• 8+ years of professional software engineering experience, with a meaningful share of that as a principal engineer or architect on a complex SaaS platform
• Deep experience as a full-stack engineer, with substantial backend depth using Ruby on Rails and the ability to engage credibly with frontend work in React
• A habit of considering alternatives, naming the trade-offs, and choosing the right path for the system in front of you rather than reaching for a textbook answer
• Confidence to put your opinion on the table, ask the questions others aren't asking, and engage in brainstorming and architectural debate
• Strong written and verbal communication, with experience working closely with product, design, QA, and infrastructure peers
• A deep foundation in computer science and a track record of making web applications highly performant
• Dedication to writing and maintaining documentation that helps others move faster
• Willingness to adapt to a fast-paced environment, to a codebase with a long history, and to a rapidly evolving AI-assisted development model
• A track record of mentorship and of raising the technical bar of the engineers around you

Technical Experience

• Large Rails codebases
• Node.js and modern JavaScript/TypeScript - we expect our Node footprint to grow and value engineers who can speak credibly across both ecosystems
• AWS and DevOps fundamentals - you do not need to be an infrastructure specialist, but you should be comfortable reasoning about deployment, scaling, and observability
• MySQL at scale, including query optimization, indexing strategies, and schema migrations on live systems
• Elasticsearch, Redis, Resque, and other supporting services in a production Rails environment
• AI-assisted development workflows, including thoughtful use of agents, prompt design, and the operational realities of keeping agentic SDLC pipelines healthy
• B2B SaaS platforms, particularly those with highly configurable customer-specific behavior

About Fluxx

• Fluxx is a people-first and inclusive workplace committed to continuous learning
• We are a global community of 400+ customers who collectively manage and distribute more than $39B in grants annually
• We build technology that drives positive impact by helping foundations, government agencies, and nonprofits streamline the grantmaking process—making it easier to get funding to the organizations that need it most
• We are committed to compliance with all applicable national, state and local laws pertaining to nondiscrimination and equal opportunity