Senior .NET Engineer

DOU Polska; Warszawa; Remote; PLN 180,000 - 250,000; Full time

Benefits offered by this job

Remote work mode

Flexible work schedule

Remote collaboration with global teams

Competitive compensation

20+ billable days off (flexible)}

Job summary

DOU Polska seeks a Senior .NET Engineer to drive a Fintech.Core module in a cloud-based fintech platform. You will lead module development, own technical quality, and steer integration decisions within a microservices architecture.

Your work will emphasize security, reliability, and performance across services. The role requires senior .NET backend experience, strong knowledge of Docker/Kubernetes, and hands-on API design using ASP.NET Web API.

Qualifications

• At least 5 years of experience as a Software Engineer.
• Professional .NET backend development experience.
• Experience with banking or fintech projects.
• Strong problem-solving and leadership in software teams.
• REST APIs using ASP.NET Web API.
• Docker and Kubernetes expertize.
• Databases: PostgreSQL, MySQL; NoSQL options.
• Experience with message queues: RabbitMQ or Kafka.
• GPRC protocol experience is a plus.
• English level B2+; Ukrainian/Polish optional.

Responsibilities

• Lead product module development on Fintech.Core and own delivery quality.
• Act as a technical expert at the module domain level and guide integrations.
• Ensure solutions meet security, reliability, and non-functional expectations.
• Design and implement scalable .NET backend services and APIs.
• Collaborate with team and stakeholders to resolve challenges.

Skills

.NET

Kubernetes

Docker

REST API

ASP.NET Web API

RabbitMQ

Kafka

PostgreSQL

MySQL

NoSQL

SQL

gRPC

AWS

English (B2+)

Tech Lead

Software Architecture

Tools

Docker

Kubernetes

AWS

PostgreSQL

MySQL

Redis

MongoDB

Apache Cassandra

RabbitMQ

Kafka

Job description

Position Overview

We are looking for a Senior .NET Engineer to drive one of our projects built on Fintech.Core, our modular white-label fintech platform. The ideal candidate will lead a product module development and take ownership of both the technical quality and efficiency within a major client deployment. The role includes acting as a technical expert at the module domain level, responsible for making integration decisions, and ensuring alignment with security, reliability, and other non-functional expectations. This position is well suited for a proactive engineer with solid experience in the fintech or related domain.

Project Description

A modular white-label fintech platform based on microservices architecture designed for financial institutions (e.g. challenger banks, PSPs, trading and payment platforms). The platform is cloud-agnostic by design and currently runs on AWS, using Kubernetes, .NET Core, PostgreSQL, gRPC protocol, RabbitMQ (MassTransit).

Current use cases

• A financial platform for a regulated institution with EMI and VASP licenses in the Philippines. The solution will combine digital banking and cryptocurrency services, including secure wallets, payments, remittances, and card issuing. A key part of the project is an in-house crypto trading module designed to provide a seamless and compliant experience for a growing global user base. The platform includes:
• Custodian wallets
• Liquidity management (Hot & Cold wallets)
• Crypto transfers
• KYT
• Trading (Matching Engine)
• Core banking
• Card issuing
• Payment processing
• A unified wealth platform combining banking, payments, digital assets, and institutional-grade yield within a single regulated ecosystem. It bridges traditional finance with modern digital markets, combining the security of licensed financial partners with the efficiency of stablecoin infrastructure. This delivers a frictionless user experience that empowers anyone to manage, earn, and spend instantly and globally. Built on a modular, compliant, and scalable architecture, it connects fiat banking, blockchain infrastructure, and off‑chain yield engines into a single system. Key features include:
• Non-custodial wallets
• Vault engine (Smart Contracts)
• Investment in Vault
• Yield Accrual
• Card transactions processing

YOUR BACKGROUND

• At least 5 years of experience as a Software Engineer
• Experience with banking or fintech projects
• Understand the big picture and offer insightful advice about technologies and projects
• Strong problem‑solving skills and the ability to manage and resolve team conflicts effectively
• Proficiency in designing and implementing software architectures
• Clean coding methodologies (SOLID, YAGNI)
• Professional .NET backend development experience
• Experience writing and using REST APIs using ASP.NET Web API
• Wide experience with Docker is required
• Experience with Kubernetes is required
• Databases: SQL {PostgreSQL, MySQL}, NoSQL {Apache Cassandra, Redis, MongoDB}
• Experience with queue (Rabbit, Kafka)
• English level — B2+
• Additional languages — Ukrainian/Polish

Skills That Will Be a Plus

• Experience in working with gRPC protocol
• Experience in solution design for complex microservice‑based architectures
• Proven experience as a Tech Lead or similar leadership role in software development
• Excellent communication and interpersonal skills, with experience in client‑facing roles
• Cloud: AWS

Responsibilities

• Lead product module development on Fintech.Core and take ownership of technical quality and delivery efficiency within a major client deployment
• Act as a technical expert at the module domain level and make sound integration decisions
• Ensure solutions align with security, reliability, and other non‑functional expectations
• Design and implement scalable .NET backend services, APIs, and integrations across the platform
• Collaborate with the team and stakeholders to resolve technical challenges and keep delivery on track

WE OFFER

• 20 billable days off in the first year of cooperation, all next years — 25 billable days off
• Fair and competitive compensation
• Friendly team and enjoyable working environment
• Clearly described business processes in the company that really work
• Regular updates on company news, Q&A sessions with top management
• Flexible work schedule
• Remote work mode
• Ability to transfer unused vacation to the next year