OpenAI Rolls Out GPT-5.5 Instant as ChatGPT's New Default Model

GPT-5.5 Instant Replaces GPT-5.3 Instant

OpenAI rolled out GPT-5.5 Instant as ChatGPT's default model for all users — including the free tier — on May 5. In the API, the model is accessible via the chat-latest endpoint, replacing GPT-5.3 Instant.

The new default delivers sharper, more concise answers and improved personalization drawn from past conversations, uploaded files, and Gmail integrations. OpenAI emphasized better reasoning capabilities and accuracy as the headline improvements over its predecessor.

Three New Real-Time Voice Models in the API

Alongside the default model change, OpenAI added three specialized voice models to the API: GPT-Realtime-2 for live voice reasoning, GPT-Realtime-Translate for real-time multilingual speech, and GPT-Realtime-Whisper for streaming transcription.

The full GPT-5.5 was released to paid subscribers on April 23; the Instant version extending access to free users marks another step in OpenAI's strategy to push its latest-generation models as broadly as possible.

Sources: OpenAI Blog · TechCrunch