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. You will work closely with our SVP of Engineering, our co-founding CTO, Director of Engineering, fellow Principal Engineers, and our product and infrastructure teams to make the right architectural calls, write meaningful code, and help the broader team raise its technical bar.

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. We are looking for someone who considers alternatives carefully, weighs trade-offs against the realities of our system, and is comfortable putting their opinions on the table and being challenged on them.

This is a full-time exempt and remote position. Candidates must be located in the United States. We aren't accepting contractors.

How you will make an impact:

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

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

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. You will work closely with our SVP of Engineering, our co-founding CTO, Director of Engineering, fellow Principal Engineers, and our product and infrastructure teams to make the right architectural calls, write meaningful code, and help the broader team raise its technical bar.

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. We are looking for someone who considers alternatives carefully, weighs trade-offs against the realities of our system, and is comfortable putting their opinions on the table and being challenged on them.

This is a full-time exempt and remote position. Candidates must be located in the United States.

How you will make an impact:

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

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 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 withou