Key Takeaways
GPT-5.3 Codex wins:
- Larger context window
- Higher intelligence benchmark
- Better at coding
- Supports vision
Step 3.5 Flash wins:
- Cheaper input tokens
- Cheaper output tokens
- Faster response time
Price Advantage
Step 3.5 Flash
Benchmark Advantage
GPT-5.3 Codex
Context Window
GPT-5.3 Codex
Speed
Step 3.5 Flash
Pricing Comparison
Benchmark Comparison
Context & Performance
Capabilities
Feature Comparison
| Feature | GPT-5.3 Codex | Step 3.5 Flash |
|---|---|---|
Vision (Image Input) | ||
Tool/Function Calls | ||
Reasoning Mode | ||
Audio Input | ||
Audio Output | ||
PDF Input | ||
Prompt Caching | ||
Web Search |
License & Release
| Property | GPT-5.3 Codex | Step 3.5 Flash |
|---|---|---|
| License | Proprietary | Open Source |
| Author | OpenAI | Stepfun-ai |
| Released | Feb 2026 | Jan 2026 |
GPT-5.3 Codex Modalities
Input
textimage
Output
text
Step 3.5 Flash Modalities
Input
text
Output
text