Senior Full-Stack Engineer (Python / React) — US or Canada only

Location: candidates must be physically based in the US or Canada, with the right to work there. Full overlap with Central Time (US) business hours.
Format: long-term contract, full-time
Rate: $30–35/h (contractor, net)
Start: early–mid December 2026

About the project
A US fintech/payments SaaS company is looking for a Senior Full-Stack Engineer to join a very small product team. The product is an AI-driven platform that helps subscription merchants recover failed payments. You will work directly with the lead engineer, with minimal hand-holding.

What you will do

• Build frontend features in React / Next.js (deployed on Vercel)
• Build backend services in Python / FastAPI (microservices on AWS), including new payment provider integrations
• Integrate external services (payment processors, email delivery) - Work with the product's AI components on the integration level - Cover merchant requests and support tasks with the lead engineer
• Write your own automated tests

Requirements

• 5+ years of full-stack experience
• Strong React and Next.js
• Solid Python (FastAPI or similar)
• Microservices on AWS, CI/CD basics
• Experience integrating LLM / AI services into a product
• Fluent, confident spoken English: you will talk to the team and merchants daily
• Self-sufficient, clear written communication, calm with on-call style interruptions

Nice to have

• Payments / PSP integrations (Stripe, Braintree, Adyen)
• Temporal or other workflow orchestration

Hiring process Screening call → technical interview → client interview → possible short take-home (3–4 h) → contract.