Senior Full Stack Engineer

The digital world never stops. Every video you stream, call you make, swipe, like, or product you buy online runs through data centers, and those consume an enormous amount of energy. That’s where Coolgradient comes in. 

We’re a green-tech start-up on a mission to make our digital lives more sustainable. Our solution, GRADIENT, is a no-code, plug-and-play optimization tool that helps data centers operate more efficiently, sustainably, and cost-effectively. Already in use across the globe, GRADIENT has saved tens of thousands of GWh in energy. And we’re just getting started! 

As we scale up, we’re looking for a collaborative Senior Full Stack Engineer to help expand GRADIENT’s reach and drive impactful change in how the world powers digital life. 

🚀 Your impact zone 

You’ll join a small development team during an exciting scale-up phase, where your contributions will directly shape the future of sustainable digital infrastructure. As a Senior Full Stack Engineer at Coolgradient, you’ll help us evolve GRADIENT into an even more powerful, intuitive, and globally impactful solution.

While this is a full stack role, your primary focus will be on backend systems design and development, building scalable, high-performance infrastructure and APIs that power the core of our platform. At the same time, you’ll bring a solid understanding of frontend technologies, contributing to the UI layer where needed and working closely with designers and product managers to ensure cohesive, data-rich experiences. You’ll also bring experience or understanding of software architecture, helping shape how our product and architecture influence each other, and how our product roadmap fits within the overall system design to keep the platform scalable and maintainable as we grow.

This is a hands-on engineering role, ideal for individuals who find energy in solving complex technical problems, building features, and staying close to the code. You’ll have space to dive deep, refine your craft, and focus on the engineering itself. 

Key responsibilities: 

• Design, build, and maintain backend services and APIs using TypeScript, Node.js, Fastify, and Sequelize ORM (v7 alpha).

• Work with OLAP/OLTP data models, with a particular focus on Snowflake or similar databases adapted for mixed workloads.

• Improve backend performance, architecture, and stability as we scale to new markets and customers. 

• Own backend components, ensuring robust, well-documented, and testable systems. 

• Collaborate with frontend developers using React and Vite. 

• Work closely with data engineering, product and UX teams to translate complex data into meaningful features. 

• Participate in Agile planning, code reviews, CI/CD workflows (GitHub Actions), and team-wide knowledge sharing.

• Contribute to architectural discussions and help ensure the platform is designed for scalability and long-term reliability.

🔋 What powers you 

We value a variety of experiences and backgrounds. If you meet most of the criteria and are excited about the role, we encourage you to apply. 

• 7-10 years of professional software development experience, with strong backend expertise in fast‑paced, product‑driven environments. 

• Solid hands-on experience with Node.js, TypeScript, Fastify, and relational/OLAP databases (Snowflake or similar preferred).

• Comfortable working with ORMs like Sequelize and open to engaging with early-stage or evolving tooling. 

• Confident operating in Docker/AWS environments, building scalable and maintainable backend services. 

• Capable of contributing to the frontend stack when needed, using technologies like React, Vite, Plotly, and TailwindCSS.

• Comfortable operating in a startup environment - adaptable, resourceful, and energized by fast-paced, evolving challenges.

• Previous exposure to architectural design or system-level thinking is a plus.

• Bonus: Experience working on SaaS applications in production environments.

🌱 A cool place to build your future 

To support your success and well-being, we offer: 

• A competitive salary, with plans underway to introduce an Employee Stock Option Plan so you can grow your stake in the company’s future. 

• Comprehensive benefits including pension, disability insurance, and a holiday allowance to support your well-being both at work and beyond. 

• A flexible hybrid setup. Blend office, home, or remote work, with hours that fit your lifestyle while staying connected with the team. 

• Mobility options including public transport subscription, company bike, or travel reimbursement for your preferred commute. 

• Strong focus on professional growth with plenty of opportunities for development and skill-building. 

• Team activities, meetups, and business events to connect and collaborate. 

😎 Cool with who you are 

At Coolgradient, we believe that diversity fuels innovation. We're dedicated to creating an inclusive environment where everyone, no matter their race, gender, age, background, ability, or identity, feels valued, supported, and empowered to thrive. We proudly welcome candidates from all walks of life to join us in building a brighter, more sustainable future together. 

💪 Ready to make an impact? 

If this sounds like you, we’d love to hear from you. Submit your CV and a brief motivation letter. A member of our team will get back to you within 5 working days. 

🐶 Note: We have an office dog! 

We know everyone’s got different comfort levels around animals, and we want our workspace to feel safe and welcoming for everyone. If you’re coming in for an interview and have any concerns, whether it's allergies, phobias, or just a personal preference, no worries at all. Just let us know, and we’ll happily keep our furry friend at home so you can feel totally at ease.