GPT-5.5, Explained Simply

OpenAI just dropped GPT-5.5, a top-tier AI model built to handle complex, professional tasks. It’s designed for developers, researchers, and anyone who needs an AI that can juggle huge amounts of information and actually use tools to get a job done right.

What it does well

• Massive memory: It has a 1-million token "context window." A token is just a piece of a word, so this means it can read and remember roughly 750,000 words at one time—like reading a whole book series without losing track of the plot.
• Image input: You can give it pictures to look at and analyze.
• Tool use: It can do a lot more than just chat. It can search the web, run computer commands (a "hosted shell"), and use other software tools to find answers or finish tasks.
• Smart thinking: It automatically uses a "medium" level of reasoning effort, meaning it takes a moment to think through problems step-by-step before answering.

What it costs and what it can handle

• Context window: Handles up to 1 million tokens at a time.
• Inputs: Can process both text and images.
• Versions: Comes in the standard GPT-5.5, plus a "GPT-5.5 Pro" version. The Pro version is meant for really tough problems that need extra computing power to solve.

Worth knowing

• Caching limits: "Prompt caching" is a trick that saves parts of your conversation to make the AI faster and cheaper to run. GPT-5.5 only supports "extended prompt caching" and does not support the quicker "in-memory" caching some older models used.
• Image detail: If you don't specifically tell the AI how much detail to use when looking at an image (leaving it on "auto"), it will fall back to its older, original way of viewing pictures.
• Where to find it: Right now, it is available through OpenAI's developer tools (the Chat Completions and Responses APIs). The Pro version is only available through the Responses API.