Senior Full-Stack Developer (Backend-Focused) — Fintech product

Hi 🙌

Umber is looking for a Senior Full-Stack Developer with a strong backend focus to join us long-term and help develop and scale a high-load payment platform.

Where you’re joining

You’ll join a team working on a payment gateway aggregator that connects merchants with local payment providers and routes transactions through different payment gateways.

The platform has been live for over two years, processes real financial transactions across five markets in Asia and LATAM, and integrates with more than 200 payment gateways.

The product is actively growing, so the team works on new integrations, platform stability, transaction processing, and improving existing solutions.

What you will do

• Develop and scale backend services for payment processing and external provider integrations.
• Investigate and resolve issues in transaction processing and provider integrations.
• Optimize PostgreSQL queries and transactional flows to support reliable system performance.
• Identify and resolve performance and reliability bottlenecks to keep the platform stable under high load as it expands into new markets.
• Contribute to architectural decisions and propose improvements to existing solutions, aligning them with the technical lead.
• Take ownership of complex technical tasks from investigation through implementation, without requiring constant guidance.
• Collaborate with the team on technical solutions, code reviews, and product improvements.
• Handle occasional frontend tasks using React when needed.

What we’re looking for

• 5+ years of commercial experience with Node.js, NestJS, and TypeScript.
• Strong experience with PostgreSQL and database performance optimization.
• Proven experience developing and maintaining high-load production systems.
• Strong expertise in backend architecture, transactional flows, and third-party API integrations.
• Experience working with microservices architectures.
• Experience with React/Next.js.
• Proactive mindset, strong ownership, and the ability to investigate complex issues, identify root causes, and independently implement reliable solutions.
• Ability to discuss technical trade-offs and propose architectural improvements.
• English level: B2 or higher.

Nice to have

• Experience in fintech, payment systems, payment gateways, or financial APIs.
• Understanding of retries, fallback mechanisms, idempotency, and fault tolerance in transaction processing.
• Familiarity with Docker, CI/CD pipelines, and infrastructure monitoring.

Our tech stack

Node.js, NestJS, TypeScript, PostgreSQL, React, microservices, Docker, AWS, CI/CD pipelines and payment provider APIs.

Hiring Process

• Call with a Talent Partner (~60-75 minutes).
• Technical interview (~1.5 hours).
• Final call with the CTO (~45-60 minutes).
• Reference/Background check.
• Final decision and offer.

Terms

Full-time · Contract-based cooperation (FOP/B2B) · 3-month probation · 24 paid days off + New Year & Christmas · Fully remote from Europe, with overlap on CET working hours · No time trackers · Annual performance review.