OpenAI launches GPT-5.5 and GPT-5.5 Pro for developers via API — faster, cheaper models now available

OpenAI released two new AI models — GPT-5.5 and GPT-5.5 Pro — available through its API (the technical interface developers use to build with OpenAI's AI). These replace or supplement the previous generation of models, with GPT-5.5 Pro positioned as the more capable version.

GPT-5.5 trades some capability for lower costs and faster response times, making it practical for high-volume tasks like customer support chatbots or content moderation. GPT-5.5 Pro offers stronger reasoning and language understanding for complex work like data analysis or coding — at a higher price point.

Developers who build on OpenAI's API now have two tiers to choose from instead of one: businesses can pick GPT-5.5 to reduce operating costs on routine tasks, or pay more for Pro when the task requires deeper thinking. This lets companies optimize spending based on what they actually need.