OpenAI
GPT-5.3 Codex
openai/gpt-5.3-codex
OpenAI’s agentic coding model for long software tasks.
TextText, Images, Files → TextReady on endue
- Coding
- Agentic work
Overview
Good for
Written by endue
- Coding
- Agentic work
Not ideal for
From the model’s specs
Nothing in the specs rules out common agent work.
Capabilities
| Tool use | Supported |
|---|---|
| Structured output | Supported |
| JSON mode | Supported |
| Reasoning | Supported |
| Vision | Supported |
| Audio input | Not supported |
| Video input | Not supported |
| File input | Supported |
| Long context | Supported |
Specifications
- Model ID
openai/gpt-5.3-codex- Family
- GPT-5 Codex
- Context window
- 400K tokens
- Input
- Text, Images, Files
- Output
- Text