Senior Integration Engineer / Senior Back-end Engineer - .NET & AWS

N-iX is a global software development service company founded in 2002, uniting 2,400+ tech professionals across 40+ countries. The company works on impactful projects for industry leaders and Fortune 500 companies, specializing in cloud, data, AI/ML, embedded software, and IoT, serving industries including finance, manufacturing, telecom, and healthcare. The client is a leading European online car marketplace with over 30 million monthly users across 18 countries.

• 3+ years of experience in AWS/cloud and .NET Core development, ideally in an integration-focused engineering role.
• Proven experience building .NET-based integration services and microservices.
• Hands-on AWS/cloud experience across development, deployment, monitoring, secure configuration, and operational support.
• Strong API integration expertise: authentication, data contracts, pagination/batching, rate limits, retries, error handling, and idempotent processing.
• Solid grounding in event-driven and asynchronous integration patterns.
• Experience with data ingestion and integration pipelines, including historical loads, incremental feeds, scheduling, and webhooks.
• Track record of ensuring data quality, reconciliation, and secure handling of financial or operational data.
• Strong collaboration, documentation, and knowledge-sharing skills within an established engineering team.
• Excellent verbal and written English skills.

Nice to have:

• HubSpot API integration experience.
• Workday API or finance/ERP integration experience.
• Data Lake ingestion and structured data landing patterns.
• CRM and operational-workflow integrations.
• Experience extending or aligning with an existing reference architecture.

• Design, build, and maintain .NET-based integration services and microservices supporting Workday-to-Data-Lake and Marketplace-to-HubSpot initiatives.
• Develop, deploy, monitor, and operationally support cloud solutions on AWS, ensuring secure configuration.
• Implement robust API integrations covering authentication, data contracts, pagination/batching, rate limits, retries, error handling, and idempotent processing.
• Build event-driven and asynchronous integration flows including webhooks, scheduling, historical loads, and incremental data feeds.
• Ensure data quality and reconciliation across integration pipelines with clear source-of-truth ownership and secure handling of financial and operational data.
• Partner with the squad's Tech Lead and team members to align with existing reference architecture, priorities, and delivery plans.
• Produce clear technical documentation and actively share knowledge within the engineering team.
• Maintain skill overlap with another integration engineer across both solutions to ensure delivery continuity.

N-iX Krakow, ​Zabłocie Business Park business centre, Zabłocie 43A, 30-70