Senior Backend Software Engineer - (m/f/x)

We are looking for a Senior Backend Software Engineer to join our cross-functional product team. You will play a pivotal role in designing, developing, and scaling the backend systems that power our AI-driven negotiation platform. You'll work closely with product managers, frontend engineers, and data teams to build robust, secure, and highly available services.

Key Responsibility: 

• Architect, develop, and maintain scalable backend services using Python and FastAPI, following Hexagonal (Ports & Adapters) architecture principles.
• Design and build serverless applications using AWS Lambda, Step Functions, and API Gateway.
• Model and manage data using DynamoDB, ensuring performant and cost-effective access patterns.
• Implement secure authentication and authorization flows using Cognito.
• Build event-driven and asynchronous workflows using Step Functions and SES for transactional messaging.
• Integrate with IoT Core to support device connectivity and real-time data ingestion.
• Ensure code quality through code reviews, automated testing, and adherence to best practices.
• Collaborate with cross-functional teams to define and deliver complete, end-to-end solutions.
• Write comprehensive unit, integration, and end-to-end tests to ensure code quality and maintainability.

• 5+ years of professional experience building and maintaining backend systems in production.
• Expert-level proficiency in Python, with hands-on experience using FastAPI.
• Hands-on experience designing systems using Hexagonal architecture (or similar patterns like Clean Architecture or Ports & Adapters).
• Strong experience with AWS serverless services: Lambda, Step Functions, API Gateway.
• Hands-on experience with AWS SAM (Serverless Application Model) for building and deploying serverless applications.
• Solid experience with DynamoDB or other NoSQL data stores, including data modeling and access pattern design.
• Experience with AWS Cognito for authentication and authorization.
• Experience with SES or similar services for transactional email/messaging.
• Familiarity with IoT Core or event-driven/IoT architectures.
• Proficient with version control systems such as Git (GitLab, GitHub).
• Familiarity with Agile development methodologies, CI/CD pipelines, and automated testing.
• Strong technical spec writing skills, with the ability to translate requirements into clear, actionable documentation.
• Excellent communication skills, a collaborative mindset, and a strong sense of ownership.

• Experience with Infrastructure as Code tools beyond SAM (e.g., Terraform, AWS CDK).
• Exposure to event-driven architectures and messaging systems (e.g., SQS, SNS, EventBridge).
• Experience with other cloud platforms (e.g., Azure, Google Cloud Platform) in addition to AWS.
• Experience using AI tools for development to boost productivity
• Integrating AI/LLM capabilities into backend systems.
• Understanding of observability practices (logging, tracing, monitoring) in distributed/serverless systems.
• Experience with containerization (Docker) and orchestration.
• Interest or experience in game theory, negotiation systems, or applied AI/ML backends.
• Experience working in regulated or high-security environments (data privacy, compliance).

• 4-Day Work Week & up to 24 Days Paid Vacation – More time to recharge
• Monthly Benefits Allowance – €40/month in vouchers for fitness and other perks with Probonio
• Competitive Compensation – Fair salary and comprehensive benefits. 
• Flexible Work Arrangements – Work the way that suits you. Professional Development – Access to training and certifications. 
• Team Events – Bi-annual company events and Quarterly team lunch get-togethers. 
• Work Abroad Flexibility – Remote work from the EU or selected non-EU countries for up to 8 weeks a year with travel insurance coverage

• In-Office Collaboration: Work from the office two days a week
• Manage Your Own Hours: Flexibility to work around your needs as long as team goals are met.