Key Takeaways
Mercury wins:
- Cheaper input tokens
- Cheaper output tokens
GPT-5.3 Codex wins:
- Larger context window
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Supports vision
- Has reasoning mode
Price Advantage
Mercury
Benchmark Advantage
GPT-5.3 Codex
Context Window
GPT-5.3 Codex
Speed
GPT-5.3 Codex
Pricing Comparison
Benchmark Comparison
Context & Performance
Capabilities
Feature Comparison
| Feature | Mercury | GPT-5.3 Codex |
|---|---|---|
Vision (Image Input) | ||
Tool/Function Calls | ||
Reasoning Mode | ||
Audio Input | ||
Audio Output | ||
PDF Input | ||
Prompt Caching | ||
Web Search |
License & Release
| Property | Mercury | GPT-5.3 Codex |
|---|---|---|
| License | Proprietary | Proprietary |
| Author | Inception | OpenAI |
| Released | Jun 2025 | Feb 2026 |
Mercury Modalities
Input
text
Output
text
GPT-5.3 Codex Modalities
Input
textimage
Output
text