AI Full Stack Developer

Leadtech Group

AI Full Stack Developer in AI-LAB building and scaling AI products with Next.js and NestJS. Collaborating on features and infrastructure in an agile environment.

Posted 6/2/2026full-timeRemote • 🇪🇸 SpainMid-LevelSeniorWebsite

Tech Stack

Tools & technologies

CloudJavaScriptNext.jsNode.jsPostgresReactTypeScript

About the role

Key responsibilities & impact

Develop and maintain features on our Next.js (App Router) frontend using TypeScript, SWR, Tailwind, and a component-driven design system, with full internationalization (i18n) support.
Design, implement, and maintain RESTful APIs with NestJS (TypeScript) to manage authentication, data processing, billing, usage tracking, and orchestration of AI workflows.
Own backend services end-to-end: from schema design and migrations to deployment and observability, and contribute to new services as the product surface grows.
Integrate and maintain third-party SDKs and APIs that power critical product flows, including payment processing, authentication, analytics, and messaging.
Build AI agents and tools using the Claude SDK and Model Context Protocol (MCP): giving LLMs real-time access to data, APIs, and tools so they can take meaningful actions on behalf of users.
Contribute to schema design with Prisma and PostgreSQL, write and review migrations, and reason carefully about data models that evolve safely over time.
Implement and maintain feature flags, A/B experiments, and analytics events so product decisions are driven by data.
Handle incoming webhooks and asynchronous task processing with the rigor required for payment-critical and PII-handling code paths (idempotency, retries, fault tolerance).
Collaborate with AI product managers and AI specialists to translate complex requirements into robust, scalable features — and push back on complexity when a simpler path exists.
Collaborate on application deployment and help maintain our cloud infrastructure.

Requirements

What you’ll need

TypeScript Proficiency: Highly proficient in TypeScript across both frontend (React/Next.js) and backend (Node.js/NestJS) environments.
Frontend Expertise: Strong experience with React and Next.js (App Router): Server Components, route handlers, streaming, metadata, i18n, and modern data-fetching patterns (SWR or equivalent).
Backend Expertise: Solid experience building production REST APIs with NestJS (or comparable Node frameworks like Express/Fastify): modules, DI, guards, interceptors, DTO validation.
Database Skills: Experience with PostgreSQL and an ORM such as Prisma. Comfortable writing and reviewing migrations, reasoning about transactions, and designing schemas that evolve safely.
API Integration Depth: Real experience integrating third-party SDKs: handling webhooks, idempotency, retries, and asynchronous fulfillment.
Problem-Solving Mindset: Collaborative, pragmatic, willing to challenge assumptions and surface tradeoffs before writing code.
Passion for AI and High Agency: Genuine enthusiasm for AI products, and a desire to bring new techniques and tools into the team proactively.
Creativity and Proactivity: You enjoy proposing features, finding creative solutions, and improving the user experience without being told to.
A serious self-learner who adapts to new tools and platforms in days, not weeks.

Benefits

Comp & perks

High-Impact Role: Be a key player in a small, agile team building a greenfield projects with the potential to transform an industry.
Modern Technology: Work with a cutting-edge, carefully selected tech stack with a focus on best practices.
Growth & Learning: Gain deep experience in AI-driven applications, cloud-native architecture, and real-time systems.
Stability & Vision: Enjoy the energy of a startup environment backed by the resources and stability of a large, successful company.
Collaborative Culture: We value open communication, teamwork, and a shared passion for building exceptional products.
Growth and career development
Work-Life balance
Comprehensive benefits
Unique Perks

ATS Keywords

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Hard Skills & Tools

TypeScriptNext.jsReactNestJSRESTful APIsPostgreSQLPrismaSWRAI workflowswebhooks

Soft Skills

problem-solvingcollaborationcreativityproactivityadaptabilitycommunicationcritical thinkingpragmatismenthusiasm for AIself-learning