Back End Developer

Backend Developer (Mid-Level) | Big Data, Real Impact

Work with large-scale data and cutting-edge tech in the heart of Copenhagen.

Are you passionate about building high-performance systems that power innovative products? Do you get a thrill from solving complex problems with clean, scalable code? At Ocean.io, we’re looking for a skilled Backend Developer to help us grow our data platform and shape the way B2B companies find and connect with their customers. 

If working with modern tech, big data, and a product-driven team in a fun and collaborative environment sounds like your thing - keep reading!

First step in our recruitment process:

No need for a boring cover letter - just upload your CV, and you’ll get a link to complete a short AI-powered interview. You can do it right away or whenever it suits you best. We use this to reduce bias and give everyone a fair chance. As an AI company, we’re all about testing new tech - including in how we hire. It’s flexible, fair, and a great way to show us who you are beyond the resume.

Who we are:

At Ocean.io, we’re changing the game for B2B customer acquisition. Our platform helps companies drive growth through smarter inbound and outbound strategies, powered by AI and massive datasets. We’re a fast-moving tech scale-up with a growing team of specialists and a culture built on trust, autonomy, and a healthy dose of curiosity. We believe in giving people ownership and room to innovate - and we think work should be fun, too.

As a Backend Developer, here at Ocean, you will…

• Backend Development: Design and implement robust, maintainable services using Python, Node.js, or Rust. Build APIs and tools that power our product and internal systems.
• Data Engineering & System Design: Help us scale and improve our large, diverse dataset by working on the full lifecycle - from crawling and ingesting data to processing, storing, and querying it efficiently.
• Product Collaboration: Work closely with our product team & the two other development teams (backend & frontend) to translate ideas into reality. You’ll be involved end-to-end - from technical design and implementation to evaluating performance and suggesting improvements.
• Innovation & Autonomy: We give you the freedom to experiment. Whether you’re optimizing an existing pipeline or proposing a new UX for our platform, we’ll support your initiatives.
• Team Collaboration: Join a supportive, international team where knowledge sharing and mutual growth are the norm. You’ll have space to work independently, but never alone.

The Stack That Powers Ocean.io

• Languages: Python (asyncio), Typescript (Node.js), Rust
• Databases: PostgreSQL, Elasticsearch, ScyllaDB, ClickHouse
• Messaging & Streaming: RabbitMQ
• Infrastructure: Kubernetes, Docker, CI/CD pipelines
• Frameworks: FastAPI, gRPC, Svelte 5

Your Tech Experience

Core Skills

These aren’t optional - they’re the bread and butter of the job.

• Strong experience with Python.
• Strong experience with developing Web applications
• Proficient with Git.

Foundations

You should be comfortable with these - they’re your launchpad.

• Solid Computer Science fundamentals.
• Experience with any modern database (SQL or NoSQL).
• Comfortable building and working with RESTful APIs.
• A creative and innovative mindset.
• Solid understanding of testing and building reliable systems.

Valuable Extras

Bonus points if you know this - it’ll give you an edge.

• Familiarity with FastAPI, SQL, Elasticsearch, or Redis.
• Experience with gRPC and/or event-driven systems (RabbitMQ or similar).
• Experience with machine learning.
• Hands-on knowledge of Kubernetes and CI/CD workflows.

But ‘what’s in it for me’, I hear you ask?

• Work with a modern tech stack and real big data challenges.
• Join a tight-knit, multicultural team that values creativity and knowledge sharing.
• Enjoy a culture of ownership, autonomy, and innovation.
• Get access to free mental health and lifestyle support through OpenUp, including 1:1 coaching, mindfulness resources, and more.
• Enjoy exclusive discounts on wellness perks like floating, massages, fitness memberships, and more - because your well-being matters too.
• Be part of a fun, social office - from daily lunch together to spontaneous Mario Kart, Darts, Card Games or Ping Pong battles.
• Work from home one day a week - no approval needed, just a heads-up to your manager.
• And of course, five weeks of holiday per year - because rest is part of the hustle too.

Sound like your next challenge?

If you’re a Backend Developer who loves building smart, scalable systems - and you’re ready to make an impact - we’d love to meet you!