Software Engineer (Back End)

We're seeking an experienced, senior back-end engineer to help develop the core platform surrounding our Workplace and TPA products. You'll work across our Rails system of record, data connectivity layer, and major feature development — the platform that runs real 401(k) plans for advisors and their business owner clients.

What makes this role different from most Rails jobs: our platform is operated by both people and AI agents. The same APIs, actions, and workflows serve human users and the agents automating our administration work, so clean contracts, permissions, staging-before-commit patterns, and audit trails are product features, not afterthoughts. You'll build the surfaces agents act through, along with the right guardrails for a complex fiduciary business.

You'll join a small, tight-knit team in a flat hierarchy inspired by the Shape Up framework, participate fully from shaping through shipping, and report to our Director of Engineering.

What you’ll do

• Own major feature development end-to-end across our products, from design doc through deployment and monitoring.
• Build the tool surfaces our agents act through: typed, permissioned, logged actions against our system of record, with staging-and-promote patterns so nothing writes to a plan without a gate.
• Design and run our data connectivity layer: recordkeeper feeds, payroll providers, payments, and identity.
• Make auditability a priority so that every action, human or agent, is traceable, explainable, and regulator-ready.
• Lead architectural discussions, write design docs, and mentor through code review.

Our stack

• Ruby on Rails / PostgreSQL on AWS ECS
• React & TypeScript on the front-end
• Redshift + dbt + Metabase; PostHog for analytics
• Stripe, WorkOS, HubSpot, Customer.io
• Agno, Langfuse, Reducto, and Skyvern on the agent side

What you bring

Required

• 6+ years of professional software development experience.
• Deep expertise in Ruby/Rails: domain modeling, background jobs, API design, performance.
• Proven track record designing scalable APIs and data models — and strong instincts for permissions, idempotency, and auditability in systems that move real money.
• Proficient working with coding agents; we're not hand-rolling boilerplate.
• Familiarity with AWS and infrastructure-as-code.
• Experience integrating third-party systems (payments, identity, CRM, payroll) and designing for their failure.
• Excellent communication skills and a collaborative mindset.

Nice to have

• Experience exposing systems to LLM agents (MCP, tool APIs), fintech or retirement domain, React/TypeScript for occasional full-stack work.