Senior Backend Engineer (Node/TS)

JOIN KLEO AND BUILD THE FINANCING INFRASTRUCTURE FOR EUROPE'S COMPANIES 🚀Kleo (www.kleohub.com) is an AI-native platform that helps compaies find, match, manage, and monitor their entire financing stack: public grants, bank lending and private capital, through automated, end-to-end workflows. We replace a process that has traditionally depended on slow, manual, relationship-driven intermediaries with software.Proactive funding!We're growing fast and we're looking for a talented Senior Backend Engineer to join the engineering team and help us scale across Europe.What you'll doPlay a key role in building and optimizing Kleo's platform using NestJS, TypeScript, PostgreSQL, REST APIs, AWS and more.Integrate AI and LLM solutions to automate financing workflows and push platform performance further.Work across both coding and DevOps, contributing to the full product lifecycle from code to deployment.Collaborate closely with the team on third-party integrations, infrastructure optimization and the ongoing development of our automated systems.What we're looking forSeniority: a senior engineer who owns development end to end, from design decisions to production, and is comfortable being accountable for what ships.Strong track record in web software development, with the judgment to make sound architectural calls and the willingness to keep learning in a fast-paced startup. As one of the first engineers, you'll have a direct impact on how the company grows.Deep command of event-driven architectures, Domain-Driven Design (DDD), hexagonal architecture and core design patterns (repository pattern and beyond), with a clear sense of when to apply them and when not to.Advanced PostgreSQL: query optimization, indexing strategy, execution-plan analysis and modelling for data-intensive workloads is a core part of the role, not a nice-to-have.Solid experience integrating AI/LLM solutions into real products, ideally in production, and an interest in turning them into reliable, automated workflows. Langchain / Mastra stacks are a plus.Strong AWS and cloud-native experience, with a DevOps mindset across the full lifecycle (containers, CI/CD, observability).English: a real intermediate-high level, especially for technical communication. No formal certification needed, but you should be able to understand and communicate technical information in English comfortably.Don't meet every single requirement? It doesn't matter. If you tick most of them and you're eager to grow and learn, apply anyway.What Kleo offersA competitive salary, matched to your experience and skills.A young, dynamic environment, sharing space with other startups in a collaborative, innovative setting.23 vacation days per year, because work-life balance matters.Real growth potential in a scaling company where your work directly shapes Kleo's success.The opportunity to participate in phantom shares in the future, so you share in the upside you help build.Hybrid model: 2 days in the office in Madrid (Cuzco area) and 3 days from home.Flexibility: a flexible schedule that fits your life and priorities. Christmas, Easter and summer are full remote if you want, August and every Friday are short-day (jornada intensiva).Why join Kleo?We're on a mission to fix financing for companies, using AI to remove the complexity and inefficiency that has held these companies back for decades.You'll join at a pivotal moment, with an essential role in the company's growth.A flexible, innovative and youthful environment, with plenty of room to learn, collaborate and develop.If you're passionate about AI, enjoy startup life and want to make a real impact in a growing company, Kleo wants to hear from you.At Kleo we welcome individuals from all backgrounds, abilities and experiences to apply, and we make employment decisions on the basis of merit. We are committed to equal employment opportunity regardless of race, color, ancestry, national origin, religion or religious creed, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender, gender identity, gender reassignment, gender expression, age, marital status, status as a protected veteran, physical or mental disability, medical condition, genetic information or characteristics, or any other legally protected characteristic.