Senior Rails Engineer -- Fintech Platform (Thoughtful Applications Only -- Cover Letter Required)

Compensation:Competitive, commensurate with experience About Topkey Topkey is a rapidly-growing fintech platform for short-term rental managers. We offer deposit accounts, credit cards, full bill-pay, external cards, and expense management—all in one Rails monolith on the latest Ruby/Rails. With $1M+ ARR, zero churn (at the time of posting this), and a small, tight-knit engineering team, you’ll have a huge impact on our roadmap, our stack, and our customers’ success. We’re backed by top-tier investors like Felicis Ventures, Andreessen Horowitz (a16z), and Y Combinator. Topkey is recognized as one of the top emerging vertical startups, and our trajectory is steep. We’re looking for driven individuals to join our team and help shape the future of financial infrastructure in the $110 billion hospitality market. We’ve been featured in numerous media outlets, includingAxios,Wall Street Journal,Fortune,Phocuswire,Short Term Rentalz, andFintech Global. What You'll DoOwn features end-to-end in our Rails monolith (Rails 8+, Ruby 3.x) Build rich, reactive UIs with Hotwire/Turbo, Stimulus, and Tailwind CSS Integrate with external APIs (Plaid, Stripe, Unit, etc.) securely and robustly Use large context LLMs (Claude, Gemini, ChatGPT, etc.) to accelerate coding, QA, and spec writing Participate in architecture discussions -- help us evolve our beautiful monolith Work closely with product and founders to take specs from prototype to prod Ship daily/weekly, review critically, and treat AI as a multiplier—not a replacement for good judgment Optimize performance, reliability, and scalability of our core platform Act as your own pair programmer—debugging, prompting, reviewing AI-generated code for quality (the eng team will also review, but the initial onus is on the contributor) You Have5+ years building production-grade Rails applications Deep expertise in Ruby, Rails conventions, background jobs, and service objects in a growing monolith Confidence reviewing, prompting, and editing AI-generated code from tools like Claude, Devin, Gemini, Cursor, etc. A reflexive approach to using AI in specs, code, QA, testing, and documentation Strong front-end chops: Stimulus/turbo/hotwire, components, etc. Experience designing and consuming REST APIs Solid SQL skills (PostgreSQL) and an eye for data modeling Track record writing maintainable test suites (RSpec) and CI pipelines Comfort working autonomously and asynchronously in a high-trust, high-output team Nice-to-HavesPrevious fintech or payments or accounting experience Familiarity with Plaid, Stripe, or similar Experience with observability tooling (NewRelic, Honeybadger, etc.) Open-source contributions or personal projects you’re proud of Contributions to open-source or side projects involving AI/LLMs Using Repomix or similar tooling for large-scale code summarization and reasoning Perks & BenefitsRemote-friendly Generous PTO and paid holidays Equity in a high-growth startup Generous professional development stipend Home-office setup budget Health, dental, and vision insurance (U.S.) + 401(k) match — *Topkey is a financial technology company and is not a bank. Banking services provided by Thread Bank; Member FDIC.#J-18808-Ljbffr