Senior Full Stack Developer – GenAI Platform (Back-end focus) - Freelance

Description

Summary: Join an AI products team as a Senior Full Stack Developer to evolve a Multi-cloud GenAI platform, focusing on Secure GPT service. Highlights: 1. Contribute to a cutting-edge Multi-cloud GenAI platform (Azure / AWS / Google) 2. Opportunity to enhance Secure GPT service with new features and capabilities 3. Engage in end-to-end development, from design to monitoring ### **Job description** Daily rate: 300€/day **Project context** ------------------- **Project Details** * Location: Barcelona * Work mode: Hybrid (1\-2 days onsite) * Start date: ASAP * Duration: Until end of 2026 * Language(s): English (Mandatory); Spanish or French (Plus) **Project Summary** We are looking for a Senior Full Stack Developer to join our AI products team and contribute to the development of a Multi\-cloud GenAI platform (Azure / AWS / Google), with a primary focus on the Secure GPT service. The role is approximately 90% back\-end and 10% front\-end. The objective is to evolve platform capabilities and ensure secure, scalable, high\-quality implementations aligned with business, technical, security, and regulatory requirements. **Goals and deliverables** -------------------------- **Main Responsibilities \& Key Activities** * Design, develop, and enhance features for the Secure GPT service: document understanding, translation, agentic capabilities, web usage, APIs, and automation * Execute end\-to\-end development activities: study, analysis, technical design, implementation, documentation, testing, and monitoring * Define and track KPIs to monitor usage and support data\-informed decisions * Collaborate within an international team and maintain regular communication with the Tech Lead and Product Owner * Implement solutions compliant with security, regulatory, and internal standards * Identify and contribute to improvements in processes, automation, and customer service delivery ### **Requirements** **Experience Required** **Mandatory Experience** * Minimum 5 years of experience in web application development, ideally within Azure environments * Back\-end development with Node.js (JavaScript / TypeScript) * Front\-end development with Next.js / React * Full ownership of the testing lifecycle: unit tests and end\-to\-end (E2E) tests * API design, implementation, and operation * Azure services: App Services, Cosmos DB, Application Insights, monitoring * DevOps practices: Azure DevOps, CI/CD pipelines * Fundamentals of Infrastructure as Code (IaC) and automation scripting * Prompt engineering: drafting, testing, and iteratively improving prompts * Experience with AI APIs and/or frameworks: OpenAI, Anthropic, Gemini, Azure AI; RAG and agentic/agent\-based capabilities **Preferred Experience** * Terraform and/or Bicep for infrastructure deployment * Observability and monitoring tooling * Background in regulated industries * Azure and API certifications * Knowledge of data security and compliance * Availability for occasional travel to France, Spain, or Portugal