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

You Have

Who you are and requirements

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