Notion reimagined its platform by deeply integrating OpenAI’s GPT‑4o, GPT‑4o mini, and embeddings across its core features. They prototyped an AI writing assistant during a hackathon and then built internal tools to rapidly evaluate and deploy new models, transforming workflows in search, note-taking, and knowledge management from static content to interactive, actionable insights.

Booking.com integrated OpenAI’s GPT models with its extensive proprietary data on properties, pricing, and availability to develop an AI Trip Planner that converts natural language queries into personalized itineraries. The team rapidly built the solution in 10 weeks by leveraging existing ML infrastructure and fine-tuning the model on both structured and unstructured data, which also powered additional tools like Smart Filters, Property Q&A, and AI Review Summaries. This innovation transformed travel discovery, search, and customer support processes.

Nubank implemented a custom AI-driven enterprise search solution by integrating GPT‑4o and GPT‑4o mini with fine-tuned domain-specific models and Retrieval-Augmented Generation techniques, enabling employees to access FAQs, policies, and internal documents rapidly. They also developed a call center copilot using GPT‑4o that integrates the bank’s knowledge base and chat history to provide real-time conversation summaries, next-reply suggestions, and step-by-step guidance for agents, and launched an AI assistant to handle Tier 1 inquiries. Furthermore, Nubank piloted a fraud quality assurance system using GPT‑4o vision to analyze transactions and visual data, ensuring robust fraud detection according to regulatory requirements.

Mercari integrated OpenAI’s API with a multi-model approach to optimize product listings. Initially, GPT‑4 analyzed top listings offline while GPT‑3.5 Turbo provided real-time suggestions for active listings. Later, they shifted to GPT‑4o mini to automatically generate complete titles, descriptions, and category suggestions from uploaded photos, streamlining the seller listing workflow.