Senior Backend Engineer - Grant Underwriting and Payment

Kikoff: The Fintech Powering Financial Security at Scale Kikoff is a profitable, pre-IPO fintech company on a mission to empower everyone to achieve financial security. With record revenue growth in 2025 and a unicorn valuation, we've built a suite of products that help millions of people build credit, access liquidity, and save money. We're scaling fast. Join us if you want to build something meaningful and help millions of people move forward financially. Why Kikoff: This is a consumer fintech startup, and you will be working with serial entrepreneurs who have built strong consumer brands and innovative products. We value extreme ownership, clear communication, a strong sense of craftsmanship, and the desire to create lasting work and work relationships. Yes, you can build an exciting business AND have real-life real-customer impact. About Grant Grant is revolutionizing financial access through our intelligent cash advance product. We're solving real customer pain points by providing fast, fair access to earned wages when life happens, without the predatory fees common in the industry. Our business model is profitable while maintaining customer-first values, and we're experiencing rapid user growth as we scale our impact. Recent Team Accomplishments Our engineering team is pushing the boundaries of what's possible in fintech infrastructure: Advanced Underwriting Engine: Developed sophisticated underwriting ML models that leverage unstructured transaction data to make instant, accurate lending decisions at scale Smart Collection System: Built ML-powered collection strategies using mathematical models and algorithms Real-Time Payments (RTP) Integration: integrated and deployed RTP rail support alongside our existing ACH infrastructure, enabling instant fund disbursement and same-day collections - a critical differentiator in our market The Role We're looking for a Senior Backend Engineer to join our Grant Core team and help us scale. You'll be working on the critical systems that power our underwriting decisions, payment processing, and collection strategies. Key Focus Areas: Payment Infrastructure: Own and scale our multi-rail payment systems (ACH, RTP, card networks) to handle transaction volume while maintaining 99.99% reliability Distributed Systems: Design and build scalable backend services that can handle millions of transactions with low latency and high throughput Background Processing: Optimize our Sidekiq job infrastructure to efficiently process complex workflows for underwriting, collections, and payment distribution System Architecture: Lead architectural decisions for our core financial systems, balancing speed, reliability, and cost as we scale Data Pipeline Engineering: Build robust data pipelines that power our ML models and real-time decision engines You'll work closely with our product and data science teams to ship features that directly impact our customers' financial wellbeing while maintaining the highest standards of reliability and security. Required Experience: 5+ years of experience with modern backend frameworks and a track record of building and scaling production systems Strong systems design skills - you've architected and shipped distributed systems that handle high throughput and maintain data consistency Production experience with background job processing systems (Sidekiq, Resque, or similar) Solid understanding of database optimization, caching strategies, and performance tuning Ideal Candidate Also Has: Experience with payment systems, financial infrastructure, or regulated environments (ACH, card processing, real-time payments) Track record of making infrastructure decisions that balance technical excellence with business pragmatism Experience working with ML/data science teams to productionize models and algorithms Background in fintech, payments, or lending infrastructure Strong system observability mindset (metrics, logging, tracing, monitoring) Technical Leadership: Ability to own co…