GPT-5.5 Instant

OpenAI

Fast default ChatGPT model (replaced GPT-5.3 Instant, May 2026). Standalone API pricing not yet published.

Text Generation API GPT Family v5.5
Parameters
-
params
Context Window
1.0M
tokens
Max Output
-
tokens
Input Price
-
per 1M tokens
Output Price
-
per 1M tokens

Capabilities

👁️
Vision
Function Calling
📋
JSON Mode
🌊
Streaming
💬
System Prompt
🖥️
Code Execution
🔍
Web Search
🔌
MCP Support

Details

Release Date
May 5, 2026
Knowledge Cutoff
December 1, 2025
Source
API
API Key Required
Yes
License
Proprietary
Model ID
gpt-5.5-instant
Last updated: May 27, 2026