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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
16,384Data policy
- Prompt retention
- Unknown — we could not confirm
- Training
- Unknown — not declared
"Unknown" does not mean "safe". It means we could not confirm it.
Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.
Frequently asked questions
- Is GPT-5.3 Chat available on FastMetal?
- Not at the moment. GPT-6.1 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.