June 27, 2026

Senior Backend Engineer (Payments focused)

Senior • Remote

4,500 - 6,000 EUR

Warsaw, Poland

Senior Backend Engineer (Payments focused)

Position Title: Senior Backend Engineer (Payments focused)
Department: Business & Product
Reports To: Technical Delivery Manager
Location: Remote / Europe
Date: ASAP
Projects & Initiatives: Multi-project

Node.js       NestJS       Stripe (Adyen, Checkout.com, PayPal)       PostgreSQL       Microservices

1. Job Purpose
We're a fast-growing tech company with a portfolio of SaaS products serving diverse
industries. Innovation, performance, and design precision are core to our values.
As we scale, we're looking for a Senior Back-End Engineer to take a key role in crafting
highly performant, maintainable, and user-focused web applications, with a strong focus on
payments infrastructure across multiple products.

2. Key Responsibilities
– Participate in daily team routines, stand-ups, sprint planning, and retrospectives.
– Actively contribute to sprint work: feature development, code reviews, and merge
requests.
– Develop testable, maintainable code; troubleshoot and debug issues as they arise.
– Gather and evaluate requirements in collaboration with the Tech Lead, Product
Manager, and fellow engineers.
– Translate requirements into solid backend features
– Integrate software components into a fully functional system
– Collaborate effectively with Product, Engineering, QA, and Customer Support
– Integrate with third-party APIs and monitor system performance
– Apply engineering best practices and agreed standards consistently
– Prepare and present technical ideas to internal teams and stakeholders

3. Requirements

MUST HAVE
– 5+ years of commercial experience with Node.js and RESTful APIs
– 1+ year of commercial experience with NestJS
– 1+ year integrating and maintaining Stripe
– 1+ year integrating and maintaining a payment orchestration platform, Primer, Gr4vy,
or Spreedly
– Proficient in English, written and spoken

ALSO REQUIRED
– Hands-on experience with the full payment lifecycle:
◦ Authorization, capture, refunds, webhooks, reconciliation
◦ Third-party API integrations
– Thorough understanding of web application and microservice architecture
– Comprehensive understanding of OOP, design patterns, and service-oriented
architecture
– Advanced PostgreSQL experience with ORM:
◦ Designing scalable schemas
◦ Performance optimization
◦ Schema and data migrations under heavy load
– Experience with unit and integration tests, e.g., Jest
– Experience with observability and monitoring in distributed environments, e.g.,
GroundCover
– Knowledge of application performance optimization techniques
– Understanding of web technologies
– Comfortable with Docker and Kubernetes
– Hands-on with modern AI development tools, e.g., GitHub Copilot, Cursor, ChatGPT,
or similar
– Strategic thinker with a problem-solver mindset
– Able to work autonomously in a fast-paced, agile, remote environment
– Strong communication skills and experience working with distributed teams

4. Nice to Have
– Experience with other payment processors, Adyen, Checkout.com, and PayPal
– Understanding of payment performance processes, EFWs, chargebacks, and refunds
– Experience with Redis
– Familiarity with CI/CD tools and practices
– Experience with AWS
– React.js / Next.js
– HTML / CSS
– Experience with SaaS products
– Past or current Tech Lead experience

5. What We Offer
– Full-time, long-term role
– 22 days paid leave + local bank holidays
– 100% remote
– Flexible hours, core window 7:00–18:00 EET
– High-traffic, global SaaS products, real scale, real impact

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Warsaw, Poland

5,000 - 7,000 EUR/mo

🏢 Summary: Senior Frontend Engineer role focused on leading development of a high-traffic web application for shipping management and rate comparison. The position involves end-to-end frontend ownership, from translating designs into production-ready interfaces to optimizing performance and accessibility. You will shape architecture decisions and maintain standards within a React/TypeScript monorepo environment. 🗂️ Requirements: 8+ years of production frontend development experience, 3+ years in senior role within scale-up or start-up environment, Deep expertise in React and TypeScript, Strong knowledge of state management and component architecture, Proficiency in HTML semantics and modern CSS, Experience with web performance optimization and Core Web Vitals, Practical expertise in WCAG 2.2 AA accessibility standards, Experience with unit, integration, and end-to-end testing, Experience working with monorepos, Ability to contribute to frontend and API architecture decisions 📃 Skills: React, TypeScript, JavaScript, HTML, CSS, Grid, Flexbox, WCAG, CoreWebVitals, Testing, Monorepo, API, AWS, Snowflake, Figma 🏢 Description: Senior Frontend Engineer Our Client is an ambitious tech company on a mission to create a frictionless shipping experience for SMEs. They wrap real-time pricing, comparison, booking, and tracking into a clean and unified interface, replacing outdated logistics processes with a seamless digital platform. Role We are looking for an experienced Senior Frontend Engineer to play a central role in shaping a web app where thousands of customers every week sign up, compare rates, manage integrations, and book shipments. You will work end-to-end—from understanding customer problems to shipping production code—while leading frontend work on a core value team (Customer Experience, Marketplace, or SaaS). Responsibilities Plan and lead frontend development within your value team, collaborating closely with PMs, designers, and backend engineers. Translate designs into production user interfaces that are accessible, performant, well-tested, and consistent with the rest of the product. Build prototypes to put working code in front of customers when validating product ideas. Own web performance on the surfaces you touch, ensuring excellent Core Web Vitals to boost conversion rates. Champion accessibility across the platform (WCAG 2.2 AA is the baseline). Contribute to architecture decisions that cross the frontend/backend line, including API boundaries and real-time updates. Maintain shared standards across a React/TypeScript monorepo through code reviews and technical councils. Mentor junior engineers and contribute to the evolution of the company's design system. Key competences 8+ years of experience writing production frontend code, with the last 3+ at a senior level in a scale-up/start-up environment. Deep React and TypeScript experience, with strong opinions on state management and component architecture. Solid web fundamentals: HTML semantics, modern CSS (Grid, Flexbox, container queries), browser rendering pipelines, and the network layer. Accessibility expertise as a practitioner skill, capable of spotting WCAG issues during design reviews. Fluency in web performance, measuring and optimizing Core Web Vitals on real products. High testing maturity (unit, integration, and end-to-end tests). Excellent written and spoken English communication skills. Bonus points for: Experience with large-scale monorepos, background in logistics/marketplaces/B2B SaaS, contributing to design systems, embedding AI-assisted features, or a working knowledge of Go. Salary and Conditions Salary up to 7000 Euro per month 100% remote from Poland B2B contract signed directly with our Client Start ASAP Benefits Work with a modern tech stack (React, TypeScript, AWS, Snowflake, Figma, Claude Code, etc.) A curious, collaborative, low-ego culture within a Great Place to Work certified environment