Senior Backend Developer

We're hiring a Senior Backend Developer to join our team in Aarhus

Build the infrastructure powering the AI revolution in ecommerce

We're looking for an experienced backend developer who wants to architect and build systems that operate at scale. This isn't about maintaining legacy code or iterating on established patterns - you'll be designing the core infrastructure that enables AI agents to autonomously optimize ecommerce operations for our customers.

You'll work at the intersection of event-driven architecture, AI agents, and real-time data processing, building systems that ingest, analyze, and act on massive amounts of ecommerce data. This is a role for someone who thinks in systems, cares deeply about code quality, and wants to shape the technical direction.

Join us on our growth journey

At Cernel, we're bringing the AI revolution to ecommerce by building the intelligent backbone behind every item sold online. We make ecommerce teams work smarter, faster, and with amplified abilities across the entire value chain - starting with what lies at the core: product data.

Our infrastructure continuously monitors and acts upon large amounts of data to drive value for ecommerce shops. We ingest customer data, process it, analyze it, and use algorithms to provide and execute optimizations autonomously on webshops.

As Senior Backend Developer, you'll report to and work closely with our CTO, taking shared responsibility for technical decisions, architecture, and building the platform that enables us to scale globally.

Responsibilities and daily work

Platform architecture and development

• Design and build core platform services (APIs, OAuth, billing services, integration layers)

• Architect event-driven systems that handle large-scale data ingestion and processing

• Build integration and data ingestion APIs that enable seamless customer onboarding

• Make architectural decisions that balance immediate needs with long-term scalability

Code quality and technical leadership

• Implement development guidelines and define code quality standards

• Write end-to-end tests and champion testable design patterns

• Define abstractions and system interaction patterns across domains

• Mentor other developers and drive technical best practices

Feature development and optimization

• Identify, design, and build features that unlock automation potential for customers

• Optimize performance and reliability of existing systems

• Support AI development teams with robust infrastructure and tooling

• Collaborate with Product and AI teams to translate requirements into scalable solutions

Technology stack evolution

• Help define and evolve our tech stack to handle increasing scale

• Evaluate and integrate new technologies that improve our capabilities

• Build systems that support our AI agents' autonomous decision-making

• Ensure infrastructure reliability and observability at scale

Technologies you'll work with

You'll have the opportunity to work with cutting-edge technologies while helping shape our future stack:

• Event-driven architecture for real-time data processing

• SQL databases for complex relationship modeling

• Temporal for workflow orchestration

• FastAPI and Pydantic for API development

• Google Cloud Platform for infrastructure

• Python and Golang as primary language

Who you are and requirements

You have:

• 5+ years of professional backend development experience

• Work onsite in Aarhus (remote not accepted)

• Deep expertise in Python, Go, or similar languages

• Proven experience designing and operating event-driven architectures

• Track record of building systems that handle scale and complexity

• Strong understanding of distributed systems, databases, and API design

• Experience with test-driven development and maintaining high code quality

Who we are

Cernel is building the next generation of ecommerce infrastructure with AI-powered agents that automate complex tasks and connect workflows across systems. We're developing an advanced agent framework that analyses data, makes decisions, and drives performance - giving ecommerce teams better results, higher conversions, and more time for creative work.

We are currently a team of 17 people working from our brand new HQ at Frederiksbjerg, Aarhus. We are ambitious, caring, and collaborative. We work hard, move fast, and genuinely care about building both a great product and a great organisation.

We value honesty, data-driven decisions, and ownership. Our team is collaborative and thrives on open communication. You'll have the responsibility and autonomy that comes with working in a startup, becoming a key resource in building the system that enables Cernel's mission.

Next steps and how to apply

The process for the role will look as follows:

• Apply and share information about yourself

• Complete personality assessment

• 60 minutes onsite interview w/ CTO and Chief of Staff

• 80 minutes technical interview w/ CTO

• Meet the team and culture fit conversation

Start date: As soon as possible