OpenAI launched GPT-5.4 on March 5 in three distinct flavors designed to address different use cases and requirements. The Standard variant provides broad capability for general tasks, the Thinking model prioritizes reasoning-first approaches, and the Pro tier delivers maximum capability for enterprise workloads. The headline feature is a 1-million-token context window that enables processing of entire books or extensive codebases in a single interaction. The model also demonstrates a 33% reduction in individual claim errors compared to GPT-5.2, marking a meaningful step forward in factual accuracy. Pricing reflects the expanded capabilities, positioning this release as OpenAI's most sophisticated offering to date.