Senior Backend Engineer

fundraiseup; Poland; On-site; USD 140,000 - 190,000; Full time

Job summary

Fundraise Up, a global fundraising platform, is hiring a Backend Engineer to design and scale services powering millions in donations. You will work on a distributed Node.js/TypeScript stack with MongoDB, Kafka, Bull/Redis, ClickHouse, and Elasticsearch, building reliable systems that handle high traffic.

You will own backend components, write tests, review code, mentor teammates, and collaborate with a Russian-speaking team.

Qualifications

• 7+ years of backend development experience in a product-driven environment.
• Strong Node.js and modern frameworks like Koa or NestJS.
• Deep TypeScript expertise with advanced typing.
• Experience with MongoDB or other NoSQL databases.
• Experience with event-driven architectures using Kafka, RabbitMQ, or Bull/Redis.
• Experience with ClickHouse and Elasticsearch.
• Strong system design and clean architecture principles.
• Ability to work independently and own projects.
• Comfortable working in a Russian-speaking team.

Responsibilities

• Design, build, and maintain backend services in Node.js and TypeScript.
• Develop new product features from concept to deployment, collaborating with product managers and frontend engineers.
• Own key parts of backend architecture for performance, reliability, and security.
• Write comprehensive unit tests and conduct code reviews to maintain quality.
• Identify and implement system improvements, refactoring legacy code where necessary.
• Mentor teammates and contribute to engineering excellence.

Skills

Backend development

Node.js

TypeScript

MongoDB

Kafka

Elasticsearch

Distributed systems

Unit testing

Code reviews

Ownership

Russian language

Tools

Koa

NestJS

Bull/Redis

RabbitMQ

MongoDB

ClickHouse

Elasticsearch

Job description

Highlights

Location: Remote (CET hours preferred)

Language: Russian-speaking team

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. You'll be joining a team where quality, mentorship, and mutual respect come first.

About the Role

As a Backend Engineer, 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.

At Fundraise Up, AI is a default tool, not an experimental one. We expect every team member to actively use AI in their day-to-day work, identify where AI can change the shape of problems in their function, and grow their fluency as the tools evolve. You should already be using AI meaningfully in your work and understand where it adds value and how it can improve the way you operate.

Requirements

• Experience: 7+ 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