Senior Software Development Engineer in Test

About Fin

Fin is a next-generation payments platform built for high-value, global, and instant transactions. We are a Series A-stage company backed by Sequoia, Circle, and other notable investors. Powered by stablecoins, Fin enables users and businesses to move millions of dollars in seconds - whether to other Fin users, directly into bank accounts, or across crypto rails. By combining the speed of crypto with the reliability and trust of traditional finance, Fin reimagines how money moves worldwide. If banks and payment products were reinvented today, they would look like Fin.

About the role

We are looking for a Senior Full Stack Engineer to join the early team and help define how money moves on Fin. You will work closely with the CEO, CTO, and a small group of senior engineers to architect the automated testing infrastructure, CI/CD pipelines, and quality standards that let Fin handle millions of transactions safely and reliably.

This is a highly autonomous role where you own projects end to end, from shaping the spec to deployment, and see your work in the hands of real users quickly. If you care about building simple products on top of complex systems and are excited about fixing how global payments work, we would love to talk.

We value your time: our process focuses on practical system design and architectural discussions, not LeetCode grinding or unpaid take-home assignments.

What you will do

• Build and own the end-to-end testing framework for our React Native mobile app and Node.js backend (using tools like Maestro, Detox, Playwright, etc.).

• Create test environments that simulate high latency, old devices, and offline-mode recovery to ensure Fin works on slow internet and fragmented device types.

• Leverage AI tools to rapidly generate test cases and edge scenarios.

• Optimize deployment pipelines (GitHub Actions) to ensure tests run fast and block bad builds automatically.

• Build scalable, high performance services that handle real money movement with strong reliability and observability.

• Maintain a high bar for code quality through clean abstractions, tests, and thoughtful code review.

What you need to be successful

• Deep experience with TypeScript and Node.js. We are mostly a TS shop with some pockets of Rust.

• Production experience with React Native. Bonus points if you are familiar with the Expo ecosystem and modern mobile build pipelines.

• Comfort configuring pipelines (GitHub Actions, CircleCI) and managing device farms (AWS Device Farm, BrowserStack, or self-hosted).

• You understand that "functional" isn't enough. You test for performance, battery drain, and network constrained environments.

• Deep comfort debugging across the stack, from database and infrastructure issues to front end performance problems.

• Solid understanding of security best practices, particularly around authentication, authorization, and handling sensitive data.

• A strong sense of code quality, including testing, readability, and maintainability in a fast moving environment.

• Clear written and verbal communication, and an ability to work closely with non engineering partners.

• High tolerance for ambiguity and the necessary shifting targets that exist in an early stage start up environment.

Bonus points

• Experience in EITHER traditional fintech integrations (Stripe, Plaid, ACH rails) OR blockchain infrastructure (especially Solana in a production environment).

• Prior startup experience where you were an early engineer and had meaningful product ownership.

• Experience setting up QA from scratch in a startup