Senior Full Stack Developer (React.js + Node.js), AI-assisted development

About the project: We’re building a member and community platform for a large not-for-profit professional association (~25,000 members across Europe). It replaces a fragmented stack of legacy tools and manual spreadsheet workflows with a single product where members sign up once, discover and register for events, pay online, network in topic communities, and check in on-site — with everything syncing automatically into the organisation’s CRM. The product ships as a responsive web app and native mobile apps from one codebase, plus an admin back-office.

Responsibilities

• Design and develop full-stack applications using Node.js/NestJS and React 19 + TypeScript;
• Architect and implement core domain features: credit-ledger integrity, real-time chat/community feeds, RBAC, event registration, and QR check-in flows;
• Build and maintain integrations with third-party services — Stripe (checkout, memberships, webhooks), Zoho CRM & Analytics, Zoom/Teams;
• Design backend APIs and services for secure, GDPR-compliant data access;
• Architect and implement AI-driven features as part of the post-MVP roadmap;
• Design and maintain prompt engineering strategies, including context management, token optimization, and output quality control, where applicable;
• Build systems that efficiently manage context windows, embeddings, and structured/unstructured data for AI features;
• Design and implement RAG pipelines where relevant to product features;
• Implement data aggregation, transformation, and enrichment pipelines (e.g., CRM sync jobs, background processing via SQS);
• Ensure performance, scalability, reliability, and observability of data-heavy and AI-heavy services;
• Rapidly prototype features using AI-assisted development tools;
• Collaborate closely with product owners and the wider team;
• Take technical ownership, perform code reviews, and mentor other engineers;
• Ability to travel internationally for individual client meetings.

Requirements

• 5+ years of professional software development experience;
• Strong backend expertise with Node.js (NestJS, Express, or similar);
• Strong frontend expertise with React (React 19 experience a plus) and modern JavaScript/TypeScript;
• Solid system design skills and experience building production-grade systems, including monorepo architecture (e.g., Nx, Turborepo, or similar), multi-surface systems (web + mobile);
• Hands-on experience integrating LLMs and AI services;
• Strong understanding of prompt engineering, token limits, context windows, and cost/performance trade-offs;
• Experience with data aggregation, transformation, and data engineering pipelines;
• Experience with SQL and NoSQL databases (PostgreSQL experience a plus);
• Understanding of data privacy and compliance principles (GDPR or similar);
• Ability to work fast, prototype effectively, and deliver high-quality solutions;
• Strong ownership mindset, leadership skills, and sense of urgency;
• Upper-Intermediate or higher English level.

Nice to have

• Experience with Capacitor or other cross-platform mobile frameworks (React Native, etc.);
• Experience with payment systems (Stripe or similar) and financial/ledger integrity;
• Experience with real-time systems (WebSockets, chat, live feeds);
• Experience building secure, compliant systems (GDPR or similar);
• Experience building RAG systems, embeddings pipelines, and knowledge bases;
• Experience optimizing AI systems for latency, accuracy, and cost;
• Background in data engineering or ML-adjacent roles;
• Experience with AWS infrastructure (RDS, S3, SQS, CloudFront, WAF).

We offer

• Competitive compensation based on your skills, experience, and performance;
• 20 working days of paid annual vacation and 5 days of sick leave;
•  3 additional days off for special occasions;
•  Experienced colleagues with 95% of middle and senior engineers;
•  Possibility to work from anywhere in the world;
•  Exciting projects involving the newest technologies;
•  Accounting as a service;
•  Flexible working approach.