Senior .NET Backend Developer (C#/.NET Core/Fintech) - Full Remote Portugal

ABOUT THE OPPORTUNITY A high-stakes fintech environment is looking for a Senior .NET Backend Developer with genuine experience in trading, brokerage, or financial services platforms. This is not a generic backend role — the client operates live financial systems where performance, security, and reliability are non-negotiable. If you've built and supported backend services in a regulated financial context and take pride in clean, scalable architecture, this is a strong opportunity to work on meaningful, complex systems from anywhere in Portugal. Language: English B2 minimum | Level: Senior | Location: Portugal-based, fully remote PROJECT & CONTEXT You'll be working on backend services and application integrations within a fintech platform, connecting back-office systems with in-house and third-party applications. The environment is live and demanding — you'll be expected to design, build, and support production-grade systems where traceability, security, and data integrity are critical. The stack centres on modern .NET, with RESTful APIs, domain-driven service architecture, and SQL Server or Oracle data layers. WHAT WE'RE LOOKING FOR At least 4+ years of C# and .NET backend development experience in production environments Minimum 2 years of hands-on experience with .NET Core 8 or .NET 10 Proven experience in application integration — connecting back-office systems with in-house and third-party platforms Strong command of RESTful API design and domain-driven service architecture principles Mandatory: prior hands-on experience in fintech, trading, or brokerage projects — this is a hard requirement, not a nice to have Experience optimising database queries and data access layers in SQL Server or Oracle Solid knowledge of secure coding practices and financial data handling requirements Familiarity with API versioning, OAuth/JWT authentication , and integration patterns Experience supporting live production systems — tracing issues, diagnosing root causes, and delivering fixes under pressure Ability to deliver scalable, maintainable backend services using modern .NET practices Strong problem-solving and analytical skills with the ability to work independently across multiple workstreams Clear communication skills in English (B2 or above) Based in Portugal , available to work fully remotely NICE TO HAVE Experience with event-driven architectures or message brokers (e.g., Kafka, RabbitMQ) in financial contexts Familiarity with CQRS and Clean Architecture patterns in .NET solutions Exposure to cloud platforms (Azure, AWS) in fintech deployments Knowledge of financial regulatory requirements or compliance frameworks (e.g., MiFID II, PCI-DSS) Experience with Docker/Kubernetes in production backend environments Compensation: €2,050 – €2,700/month net, depending on experience and seniority level. Why HumanIT people stay (4.4 Glassdoor, 89% recommend) - 15th month salary - Health insurance covering your family - Birthday off - Mobility program for digital nomads - Real work-life balance Full benefits https://www.humanit.pt/careers/#perks What it's really like https://www.humanit.pt/careers/#work-at