Carlos Ortiz

Founded and built ReactChallenges.com, a full-stack Next.js SaaS for practising React technical interviews. Grew it solo from zero to 2,000+ registered users, owning product, engineering, and growth.

Owned the frontend architecture of Design Workflow, a React + Rete.js visual editor that compiles node-based flows into CWL. Set the technical roadmap, led the frontend team, and established the testing foundation with Vitest and Playwright.

Built one of the earliest ChatGPT-powered customer-service assistants, implementing the entire RAG pipeline by hand (chunking, OpenAI embeddings, Pinecone vector search, context assembly) and integrating it into WooCommerce via a custom WordPress plugin.

Led full-stack development across Network Rail's corporate web estate, including the flagship corporate site, microsites, SPAs, and internal products. Introduced a Storybook-based design system and brought outsourced development in-house, saving thousands of pounds.

Built and optimised WordPress sites for clients including Volkswagen Financial Services and Peach Pubs. Owned the full stack of each build, from custom themes and plugins to Cloudflare DNS/CDN, with a strong focus on page speed and search performance.

Degree in Building Engineering from Universidad de Extremadura, completed in 2002.