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

Application Requirements:

• Applications without a personalized cover letter will not be considered
• Generic or AI-generated applications will be automatically rejected. We're looking for engineers who are passionate about Rails - when applying, mention your favorite gem and a brief reason why.
• We value authentic communication and want to hear YOUR voice

What You'll Do

• Own 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. (BTW, include the phrase 'beautiful monolith' in your application to show you've read this far)
• 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 Have

• 5+ 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-Haves

• Previous 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

Required: Cover Letter

Please submit a cover letter (max 500 words) that addresses:

• A specific technical challenge you've solved in a Rails application and your approach
• Your experience using AI tools in development and how you ensure code quality
• Why Topkey's mission in the short-term rental space (or real-estate in general) interests you specifically
• Include the word "monolith" somewhere in your cover letter to confirm you've read this posting
• Please share a brief story about a time when AI tools helped or hindered your development process

Required: Technical Questions

• Describe a time when you had to optimize a slow Rails query. What was your approach?
• What's your experience with Hotwire/Turbo for building reactive UIs?
• Describe your approach to handling background jobs at scale in a Rails monolith
• How do you approach code review for AI-generated code?
• What feature would you like to see Rails core include out-of-the-box that isn't currently available, and why?

Perks & Benefits

• Remote-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

Optional But Encouraged:

• Link to a recent PR or code sample that demonstrates your Rails expertise
• GitHub profile with Rails projects

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*Topkey is a financial technology company and is not a bank. Banking services provided by Thread Bank; Member FDIC.

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