Senior Full Stack AI Native Developer

About Leadtech: Leadtech is a premier, hyper-growth digital platform innovator and software services collective dedicated to creating exceptional user experiences and data-driven web solutions globally. By combining the high-velocity agility of a greenfield startup ecosystem with the stable, long-term corporate backing of a highly successful enterprise, Leadtech engineered a cutting-edge artificial intelligence platform designed to address complex real-world operational challenges. Operating across high-performance remote hubs and an award-winning waterfront design center in Barcelona, Leadtech prioritizes technical excellence, open communication, and the continuous learning development of its engineering talent.

Position Overview

We are seeking a highly analytical, systems-minded Senior Full Stack AI Native Developer to join our core Development team in a permanent, full-time remote capacity within Spain. In this highly autonomous, execution-heavy software engineering seat, you will work directly across our entire cutting-edge AI stack, deploying scalable technical features with a rapid, fast-shipping methodology. Moving far beyond basic layout modification, you will claim individual accountability for designing stateful multi-agent workflows, managing multi-tier data pipeline scripts, and orchestrating complex decision logic trees natively in JavaScript, TypeScript, and Python. This high-agency role demands a creative problem-solver who can master newly emerging platform SDKs in days, build clean RESTful microservices, and transform abstract user vision parameters into resilient runtime architectures.

Key Responsibilities

• AI Agentic Workflow Engineering: Architect, code, and deploy highly collaborative multi-agent software networks natively using LangGraph, LangChain, and LangFuse to manage complex decision logic trees and conditional states.
• Model Context Protocol Integration: Implement advanced Model Context Protocol (MCP) data agents using the Claude SDK, connecting real-time platform metrics, relational webhooks, and external programmatic tools directly with large language models.
• Next.js Server-Side Development: Model, secure, and maintain low-latency RESTful APIs and internal data services utilizing TypeScript, Node.js, Next.js, and Express backend routing modules.
• Interactive Interface Programming: Code intuitive, high-performance web user interfaces using React, TypeScript, and Vite, allowing seamless client-side media uploads and graphical analytics management.
• External Service Aggregation: Connect core business workflows with high-volume Payment Service Providers (PSPs) and third-party vendor platforms, managing incoming asynchronous webhook queues.
• Relational Schema Migration: Design structural database models, refine transactional tables, and execute schema migrations across PostgreSQL and Google Cloud BigQuery repositories.
• Cloud Infrastructure Architecture: Collaborate closely alongside infrastructure squads to handle multi-tenant application deployments and optimize underlying resources across the Google Cloud Platform (GCP).

Required Skills & Qualifications

• Proven professional history running full-stack web application development, backend systems engineering, or artificial intelligence product architecture.
• Deep, authoritative technical command building high-concurrency applications using TypeScript natively within both frontend (React) and backend (Node.js) runtime structures.
• Hands-on operational experience creating and orchestrating structured AI agent workflows utilizing LangGraph, LangChain, or equivalent large language model (LLM) orchestration SDKs.
• Solid experience writing relational database scripts, managing database connections, and deploying software components inside PostgreSQL systems.
• Strong programming literacy with python-centric workflows, web framework libraries, and multi-layered API integration layers.
• Outstanding verbal and written communication mechanics, showing high personal agency and a passion for turning complex product vision into clean, maintainable systems code.
• Location Context: Full-time remote parameters open exclusively to qualified full-stack software engineers based permanently anywhere within Spain, with optional access to the Barcelona corporate office.

Preferred Strategic Indicators (Nice to Have)

• Prior experience building scalable software models around digital media processors, streaming components, or cloud analytics layers.
• Practical familiarity navigating infrastructure resource dashboards natively within the Google Cloud Platform (GCP).
• Familiarity with enterprise component libraries, design system design rules, and continuous integration (CI/CD) tooling configurations.

What We Offer

• High-Impact Greenfield Runway: The exceptional professional canvas to directly program, own, and expand a breakthrough AI-native architecture transforming global corporate capabilities.
• A permanent full-time employment contract accompanied by an experience-calibrated competitive base salary structure and transparent promotion pathways.
• Profound work-from-home remote parameters offering high scheduling flexibility, complete geographic freedom across Spain, and a robust emphasis on healthy work-life balance.
• Elite Summer Working Hours: Enjoy free Friday afternoons year-round with a 7-hour daily schedule, supplemented by a reduced 35-hour workweek throughout July and August.
• Comprehensive health care provisions, including premium private health insurance coverage (inclusive of complete dental, optical, and psychological clinical services).
• An annual learning development budget alongside custom internal courses, 25 days of paid vacation plus your birthday off with zero blackout windows, and gross-salary direct vouchers for restaurant tickets and nurseries.
• Premium beachfront office privileges in Barcelona complete with free snacks, fresh fruits, premium coffees, specialized gaming rooms, and rooftop terraces overlooking the Mediterranean Sea.