Principal Engineer

Fluxx is looking for a highly motivated Principal Engineer to join the Engineering team. As a Principal Engineer at Fluxx, you'll be a senior technical leader on our engineering team, responsible for driving the architecture and implementation of large, cross-cutting initiatives on our grantmaking platform. This is a hands-on role. You'll spend the majority of your time in code, working through real problems and deliverables end-to-end, and the rest of your time on design, technical direction, and unblocking others. This is a full-time exempt and remote position. Candidates must be located in the United States.

Responsibilities

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; Lead and drive best practices with the team across the entire SDLC; Mentor engineers across the team, raise the architectural literacy of the group, and actively contribute to brainstorming and design discussions; Represent the engineering organization in leadership discussions and occasionally in direct conversations with customers; Champion thoughtful use of AI and agents in our SDLC, helping the team amplify their work

Requirements

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; Deep experience as a full-stack engineer, with substantial depth using NodeJS and 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; Proven ability to navigate complex technical trade-offs, ensuring rapid feature delivery without compromising long-term platform scalability; Node.js, React and modern JavaScript/TypeScript; Large Ruby on Rails codebases - you should be able to 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

Nice to have

Go; Python; Java; other modern languages used in systems targeting high-performance and concurrency features

Benefits

Medical, dental, and vision insurance; Flexible time off; Paid sick leave; 12 weeks of fully-paid parental leave; Annual learning and development stipend; Internet stipend; One-time home office set-up stipend; 401(k) retirement plan with company match; Incentive stock options