Overview
GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2.
GPT-5.3-Codex is available in OmnyChat. 400,000 token context window. Image input. Reasoning mode. Tool calling.
Key capabilities
- 400,000 token context window
- Image input
- Reasoning mode
- Tool calling
Using this model
In OmnyChat
Use GPT-5.3-Codex in OmnyChat and compare its results with other language models on the same task.
Best for: Chat and comparing answers on your own prompts.
Frequently asked questions
How do I use GPT-5.3-Codex?
Open chat in OmnyChat and select GPT-5.3-Codex. Model access and usage depend on your plan.
What does GPT-5.3-Codex support in OmnyChat?
400,000 token context window. Image input. Reasoning mode. Tool calling.