Senior Full-Stack Engineer (Node.js / React)

Ukraine, Europe Full Time Active

About the Client

The fintech platform that helps businesses reduce payment processing costs. It analyzes transaction and fee data to identify interchange downgrades, monitors payment performance, and optimizes transaction data before it reaches the processor.

The Role

You will join a small, senior engineering team working directly with the Founder & Product Owner to build and scale the platform.

This is a high-ownership role covering the full stack, from payment data ingestion and backend services to customer-facing React applications. We’re looking for someone who can own features end-to-end, ask the right questions, and work independently without requiring detailed step-by-step direction.

Key Responsibilities

• Build asynchronous pipelines for payment transaction and fee data.
• Integrate with payment processors via APIs, webhooks, and SFTP.
• Analyze Visa and Mastercard rules using AI-assisted document processing.
• Detect interchange downgrades and improve transaction data quality.
• Build and maintain Node.js backend services and React dashboard features.
• Deploy and operate services on AWS using ECS and Docker.
• Own features from implementation through testing and production delivery.
• Work directly with the Product Owner on requirements and technical solutions.

Required Qualifications

• 8+ years of professional software engineering experience.
• Strong Node.js and React experience.
• Experience with payments, fintech, or financial integrations.
• Experience with asynchronous/event-driven systems and data processing.
• Strong AWS, Docker, and PostgreSQL experience.
• Experience with API and SFTP-based integrations.
• Strong ownership and ability to work independently.
• Proactive communication and willingness to ask questions and clarify assumptions.
• Comfortable working in a small team and an evolving product.
• Intermediate spoken English or higher.

Nice to Have

• Experience with Stripe, Adyen, Fiserv, Worldpay, or similar p.rocessors
• Knowledge of interchange, Visa/Mastercard rules, or L2/L3 payment data.
• Experience applying AI/ML to document or data processing.
• Previous startup or small product team experience.

Your Recruiter

Alla Gokturk

Lead of Recruitment — Waverley Software