Modelpeers

GPT-5.5 and GPT-5.5 Pro

2 models from OpenAI

New release

GPT-5.5 and GPT-5.5 Pro released in the API

GPT-5.5 shipped to the Chat Completions and Responses APIs, with GPT-5.5 Pro on the Responses API. Reasoning effort defaults to medium, and caching for GPT-5.5 only works with extended prompt caching.

Who is affected:
Developers choosing a frontier OpenAI model on the API.
What to do:
Test GPT-5.5 against your current model. Note that in-memory prompt caching is not supported.

Source

"GPT-5.5 supports a 1M token context window, image input, structured outputs, function calling, prompt caching, Batch, tool search, built-in computer use, hosted shell, apply patch, Skills, MCP, and web search."

OpenAI API changelog

Published

Open the sourcedevelopers.openai.com

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