Senior Backend Engineer (Full-Stack Integration) – Sustainable Tech Unicorn

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About the client:

A German Sustainable Tech Unicorn that is redefining how global corporations handle transparency. Backed by a 130M Series C investment our client has built a proprietary serverless cloud infrastructure to ensure human rights and ecological responsibility across global supply chains.

Currently in a massive consolidation phase their Madrid Hub is expanding from 20 to over 100 top-tier engineers in 2026. This is your chance to join a high-growth environment where engineering quality and product ownership are the top priorities.

Job description:

As a Senior Backend Engineer you will be the backbone of our client transparency engine. While your expertise lies in robust server-side architecture you will own your features from the database to the final user interface ensuring a seamless bridge between complex ESG data and the end-user experience.

The Mission: Engineering Beyond the API

Our client a German Sustainable Tech Unicorn (130M Series C) operates a high-scale serverless ecosystem. We need an engineer who doesnt just hand over an API but who understands how data should be consumed and presented to solve critical global supply chain challenges.

Key Responsibilities:

• Core Backend Excellence: Architect develop and maintain high-performance microservices and serverless functions ( Ownership: Take responsibility for vertical slices of the product. This includes designing the schema building the logic and implementing the necessary React hooks/components to bring the feature to life.

• System Design: Lead the evolution of our serverless Hub focusing on data consistency security and scalability.

• Contract-First Development: Define and maintain the TypeScript interfaces that unify our backend and frontend ensuring type safety across the entire stack.

• Technical Mentorship: Drive backend best practices while helping the team maintain a high standard of frontend integration and performance.

Your Profile

• Backend DNA: 6 years of experience with a mastery of and TypeScript. You are an expert in asynchronous patterns API design and distributed systems.

• Pragmatic Full-Stack Ability: You are a Backend Engineer by trade but you are proficient enough in to build and maintain the interfaces that power your services. You believe that a done feature includes its visual implementation.

• Infrastructure & Cloud: Strong experience with AWS (Serverless) event-driven architectures and SQL/NoSQL databases.

• Product Mindset: You care about the Why as much as the How. You build tools that provide real value to 2000 global companies.

• Communication: Fluent English (C1).

Whats in it for you

• The Unicorn Experience: Impact at scale within a high-density engineering hub in Madrid.

• Hybrid Model: 3 days office / 2 days remote.

• Tech Sovereignty: You own the stack. From the database query to the React render you have the autonomy to build it right.

• Top-Tier Package: Competitive salary monthly specialized benefits.