About GPT 5.3 Chat
GPT 5.3 Chat is the GPT-5.3 Instant model used in ChatGPT as the default for chat applications. It features a 128,000-token context window optimized for conversational use, with support for text and image inputs, streaming, function calling, and structured outputs. OpenAI suggests using GPT-5.2 or newer for API deployments.
| Metric | Value |
|---|---|
| Context Length | 128,000 tokens |
| Max Output Tokens | 16,384 tokens |
| Multilingual | Yes |
Ready to build with GPT 5.3 Chat?
Try GPT 5.3 Chat in the Workbench to prompt it, compare outputs, and iterate on prompts without writing any code. When you're ready to ship, call the same model from our API and build your own apps on top of it.
curl -sSf -X POST https://hub.oxen.ai/api/ai/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer $OXEN_API_KEY" \
-d '{
"model": "gpt-5-3-chat-latest",
"messages": [
{
"role": "user",
"content": "Try sending a message."
}
]
}'API endpoint
See the API reference for request and response formats.
POST
https://hub.oxen.ai/api/ai/chat/completions