Backend Developer (Node.js)

Fundraise Up

Location: Poland
Job Type: full-time
Salary: €5,100 - €6,300
Posted: September 5, 2025

Job Description

About Fundraise Up

We’re Fundraise Up - a global fundraising platform built to make donating to nonprofits fast, seamless, and accessible to all. Every month, our technology powers tens of millions of dollars in donations across the globe. We focus on innovation that directly impacts results: faster load times, higher conversion rates, global payment support, and accessibility-first design.

Our platform is trusted by many of the world’s leading nonprofits, including UNICEF, the Alzheimer’s Association, and a wide range of global NGOs. With a 4.9/5 rating across top software review platforms, we’re recognized not just for our impact - but for the quality of the product we deliver.

A Truly Global Product

We operate in the enterprise segment, serving nonprofit organizations across North America, the United Kingdom, Australia, and Europe.

We’re building a large and complex product ecosystem that serves nonprofits, donors, and partners around the world. The platform includes a modern checkout experience and customizable widgets (each a standalone SPA), donor, organization, and partner portals, admin tools, and several internal apps.

Our backend is powered by Node.js (Koa, NestJS) and MongoDB. The frontend stack includes Webpack, Vue.js, and React, with nearly all code written in TypeScript. For high-throughput messaging and background processing, we use Kafka (for millions of events) and Bull (Redis). Analytics data is stored in ClickHouse, and we use Elasticsearch for search.

The Team

We are a distributed team of 160+ product professionals, including 80+ engineers. Our team members are mainly based across Spain, Poland, Portugal, Georgia, Armenia, Serbia, Turkey, and Cyprus. Many of our developers bring 5 - 10+ years of experience, and we foster a culture of deep technical curiosity and knowledge sharing.

Despite our scale, we operate like a focused team - where every task matters and every voice is heard. We value thoughtful collaboration, strong engineering practices, and a product mindset. Biweekly engineering forums give space to share learnings and celebrate technical achievements. You’ll be joining a team where quality, mentorship, and mutual respect come first.

About the Role

As a Backend Developer, you will be a key architect of the engine that powers our global platform. You'll resolve complex challenges in a high-load, distributed system, building and scaling the infrastructure that processes millions in donations. This is not a maintenance role; it's a high-impact, product-focused engineering position where clean architecture, performance, and reliability are paramount.

You will work on a complex product ecosystem—from our modern checkout experience to donor portals and massive analytics pipelines—all powered by a cutting-edge tech stack.

Backend: Node.js (Koa, NestJS), TypeScript
Database: MongoDB
Infrastructure: Kafka for event streaming, Bull (Redis) for background jobs, ClickHouse for analytics, and Elasticsearch for search.

What You'll Do

Design, build, and maintain clean, efficient, and scalable backend services in Node.js and TypeScript.
Develop new product features from concept to deployment, collaborating closely with product managers and frontend engineers.
Own key parts of our backend architecture, making critical decisions that enhance performance, reliability, and security.
Write comprehensive unit tests and conduct thorough code reviews to maintain code quality.
Proactively identify and implement system improvements, refactoring legacy code where necessary.
Contribute to a culture of engineering excellence by mentoring others and sharing your expertise.

Requirements

Experience: 5+ years of backend development experience, preferably in a product-driven environment.
Node.js Expertise: Strong, hands-on experience with Node.js and modern frameworks like Koa or NestJS.
TypeScript Pro: Deep expertise in TypeScript, including its advanced typing and module systems.
Database Skills: Solid experience with MongoDB or other NoSQL databases.
Distributed Systems: Familiarity with event-driven architecture using tools like Kafka, RabbitMQ, or Bull/Redis.
Data & Search: Hands-on experience with ClickHouse (or similar analytics DBs) and Elasticsearch.
Architectural Mindset: A strong understanding of system design, clean architecture principles, and performance optimization.
Ownership: The ability to work independently, take ownership of your work, and see projects through to completion.
Communication: Comfortable working within a Russian-speaking team.

Nice to Have

Prior experience working in a remote-first, globally distributed team.
Experience with performance monitoring and observability tools (e.g., Prometheus, Grafana, Datadog).
A genuine interest in the non-profit technology sector.
A hypothesis-driven mindset and the ability to communicate complex technical concepts to non-technical stakeholders.

Bonus points

Curiosity and a hypothesis-driven mindset
Ability to communicate complex analytical concepts to non-technical audiences
Detail-oriented with a strong sense of ownership
Comfort working in fast-paced, data-rich environments

Why work with us

A strong, collaborative product team that owns what it builds
Clear product vision and access to real customer feedback from global nonprofit leaders
Flat structure: no politics, just great work with great people
Transparent company culture-we share how we’re growing, where revenue comes from, and what’s next
Long-term focus: we offer equity options and value sustained, meaningful contribution

Benefits

31 days off
100% paid telemedicine plan
Home Office Setup Assistance: the company offers assistance with purchasing furniture (office chair, office desk, monitor) and other items to create a comfortable workspace.
English learning courses
Relevant professional education
Gym or swimming pool
Co-working
Remote working

_{**Please note: All official correspondence from Fundraise Up will exclusively originate from the @fundraiseup.com domain. Exercise caution and ensure the authenticity of emails claiming to be from our company.}

🎯 Who is this job for?

This role is ideal for a Senior Backend Developer with 5+ years of experience in Node.js (Koa or NestJS) and TypeScript. Candidates should be proficient with MongoDB, distributed systems using Kafka or Redis, and familiar with ClickHouse, Elasticsearch, and clean architecture principles. Fluency in Russian and experience in high-load, scalable backend systems are essential.

💬 Potential Interview Questions

What are the main advantages of using NestJS over Koa in Node.js backend development?
NestJS provides a modular architecture, dependency injection, and TypeScript support out of the box, while Koa is more lightweight and flexible but requires more manual setup.
How would you design a scalable background job processing system in Node.js?
By using tools like Bull (Redis) for job queues, ensuring retry mechanisms, monitoring job execution, and scaling workers horizontally based on system load.
What are some best practices for writing clean and maintainable TypeScript code?
Using strict typing, avoiding any, leveraging interfaces and generics, enforcing linting rules, and organizing code into clear modules.
How does MongoDB differ from relational databases, and when would you choose it?
MongoDB is schema-less and document-oriented, allowing flexible data models and horizontal scaling. It’s ideal for high-throughput, dynamic applications where schema changes are frequent.
What role does Kafka play in an event-driven architecture?
Kafka acts as a distributed streaming platform, enabling services to communicate asynchronously, handle high event throughput, and ensure fault tolerance.
How would you optimize queries in Elasticsearch?
By using proper indexing, limiting the number of fields, applying filters before full-text search, using aggregations efficiently, and monitoring query performance with profiling tools.
What are the key principles of clean architecture, and how do they apply to backend services?
Separation of concerns, dependency inversion, and keeping business logic independent of frameworks. This ensures testability, maintainability, and scalability.
How would you handle fault tolerance in a distributed Node.js system?
By implementing retries with backoff, using circuit breakers, designing idempotent operations, and leveraging message queues for resiliency.
What are the trade-offs between using ClickHouse and MongoDB for analytics?
ClickHouse is optimized for OLAP queries with large datasets and aggregations, while MongoDB is better for operational workloads. Choosing depends on whether the use case is transactional or analytical.
How do you approach testing in a Node.js backend project?
By writing unit tests with Jest or Mocha, integration tests with a test database, using mocks for external services, and setting up CI pipelines to run tests automatically.

📋 Job Summary

Fundraise Up, a global platform powering millions in nonprofit donations, is hiring a Backend Developer (Node.js) to join its remote, Russian-speaking team. You'll work with Node.js (Koa, NestJS), TypeScript, MongoDB, Kafka, and Redis to build scalable systems for high-load, distributed environments. The role offers €5,100–€6,300/month + stock options, 31 days off, full remote setup support, and a mission-driven, engineering-focused culture. Join a fast-growing company making a real impact for organizations like UNICEF and the Alzheimer’s Association.