Is GPT-5.3 Chat available on FastMetal?

Not at the moment. GPT-5.6 Sol, from the same lab, is available on the FastMetal API today.

What is the context window of GPT-5.3 Chat?

128,000 tokens, shared between the prompt and the response.

openai/gpt-5-3-chat

Not Available

GPT-5.3 Chat

GPT-5.3 Chat is an update to ChatGPT's most-used model that makes everyday conversations smoother, more useful, and more directly helpful. It delivers more accurate answers with better contextualization and significantly reduces unnecessary refusals, caveats, and overly cautious phrasing that can interrupt conversational flow.

3/3/2026

128,000 tokens

Specifications

Modalities

Input

text

image

file

Output

text

Supported Parameters

max_tokens

response_format

seed

structured_outputs

tool_choice

tools

Max Output Tokens

16,384

Frequently asked questions

Is GPT-5.3 Chat available on FastMetal?: Not at the moment. GPT-5.6 Sol, from the same lab, is available on the FastMetal API today.
What is the context window of GPT-5.3 Chat?: 128,000 tokens, shared between the prompt and the response.

Models you can use on FastMetal