GPT-5.3 Chat

Retired

OpenAI · March 2026

OpenAI retired this model on 10 August 2026, so you can't start new chats with it. Use GPT-5.6 Sol instead. Your previous conversations are still available.

The build that ran ChatGPT for GPT-5.3. Tuned for conversation; answers straight away.

Best for: Everyday chat
Use instead: GPT-5.6 Sol

Context window
128,000 tokens
≈ 96,000 words · about 380 pages
Max output
16,384 tokens
≈ 12,000 words in a single answer
Knowledge cutoff
August 2025
its training cutoff

Modalities

TextInput and output
ImageInput only
AudioNot supported
VideoNot supported

Features

StreamingSupported
Function callingSupported
Structured outputsSupported
Fine-tuningNot supported

Tools

Web searchSupported
Tool searchNot supported

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