OpenAI · Flex
GPT-5.3 Codex
Maximum Coding Intelligence
Context window
400K
tokens
Max output
128K
tokens
Tier
Flex
access
Pricing
Input
$1.75
per 1M tokens
Output
$14.00
per 1M tokens
Overview
Overview
GPT-5.3 Codex represents OpenAI's most advanced coding model, purpose-built for complex, long-horizon agentic coding tasks. It combines maximum intelligence with deep reasoning capabilities for the most demanding software development challenges.
Best Use Cases
✅ Recommended For
- Complex Coding: Long-horizon, multi-step software development tasks
- Agentic Workflows: Advanced autonomous coding agents with complex orchestration
- Architecture Design: High-level system design and refactoring
- Code Analysis: Deep analysis of large codebases and complex systems
⚠️ Consider Alternatives For
- Simple Tasks: Codex Mini offers better cost efficiency for routine coding
- Cost-Sensitive Projects: Codex Mini provides 5x lower cost for simpler tasks
Technical Highlights
| Feature | Details |
|---|---|
| Context Window | 400K tokens |
| Max Output | 128K tokens |
| Pricing | $1.25 / $10 per MTok (in/out) |
| Knowledge Cutoff | September 2024 |
| Reasoning | ✅ XHigh effort level |
| Tool Use | ✅ Advanced function calling |
| Vision | ✅ Text and image input |
| Web Search | ✅ Supported |
| API Method | Responses API only |
Capabilities
- Premium
- Coding
- Reasoning
- Agentic
Recommended for
- Coding
- Complex Agents
- Long Horizon Tasks