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

Nnamu; Berlin, München; Hybrid; EUR 110,000 - 170,000; Full time

Benefits offered by this job

4-day work week

Benefits allowance

Professional development

Team events

Remote work abroad

Job summary

Beroe X nnamu GmbH in Berlin is seeking a Senior Backend Software Engineer to design, develop, and scale backend systems powering our AI-driven negotiation platform.

You will architect serverless services with Python and FastAPI, leverage Hexagonal architecture, and work across product, data, and frontend teams to deliver robust, secure solutions. The role emphasizes ownership, testing, and high availability.

Qualifications

• 5+ years of backend experience in production systems.
• Expert-level Python with FastAPI.
• Experience with Hexagonal architecture patterns.
• Strong knowledge of AWS serverless services (Lambda, Step Functions, API Gateway).
• Experience with AWS SAM for deployment of serverless apps.
• Solid modeling and access patterns in DynamoDB.
• Experience with Cognito for auth and SES for transactional messaging.
• Familiarity with IoT Core and event-driven architectures.
• Proficient in Git and CI/CD pipelines.
• Strong collaboration, writing, and documentation skills.

Responsibilities

• Architect, develop, and maintain scalable backend services.
• Design serverless apps using AWS Lambda, Step Functions, and API Gateway.
• Model data with DynamoDB and ensure performant access patterns.
• Implement secure authentication and authorization with Cognito.
• Build event-driven workflows and integrate with SES for messaging.
• Integrate IoT Core for device connectivity and real-time data ingestion.
• Ensure code quality via reviews, testing, and best practices.
• Collaborate with cross-functional teams to deliver end-to-end solutions.
• Write unit, integration, and end-to-end tests to sustain quality.

Skills

Python

FastAPI

Hexagonal architecture

Agile

CI/CD

Testing

Git

Education

Bachelor's degree in a relevant field

Tools

AWS Lambda

Step Functions

API Gateway

AWS SAM

DynamoDB

Cognito

SES

IoT Core

Docker

Job description

Your tasks

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.

Your profile

• 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.

Bonus Qualifications

• 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).

Why us?

At Beroe X nnamu GmbH, we prioritize a balanced work-life experience.
Here’s what we offer you:

• 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

We operate on a hybrid model with offices in Berlin and Munich, offering a 32-hour, 4-day workweek.

This means:

• 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.

Our Culture

We are committed to fostering a collaborative, innovative and inclusive work environment where everyone’s ideas matter.

We know that diverse teams lead to better outcomes and welcome applicants from all backgrounds.