Claude 3.5 Sonnet v2 vs GPT-5.3-Codex
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Claude 3.5 Sonnet v2 and GPT-5.3-Codex.
Claude 3.5 Sonnet v2
Claude 3.5 Sonnet v2 is Anthropic's enhanced version of the breakthrough Claude 3.5 Sonnet, delivering significantly improved coding capabilities, longer context handling, and more reliable tool use at the same competitive pricing. It maintains the same 200K-token context window while achieving substantial gains in HumanEval, SWE-bench, and agentic task completion rates. Claude 3.5 Sonnet v2 remains widely used as a fallback model for teams that have standardized on the 3.5 architecture and prefer its consistent, well-characterized behavior for production deployments.
GPT-5.3-Codex
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. It achieves state-of-the-art results...
Technical Specifications
| Specification | Claude 3.5 Sonnet v2 | GPT-5.3-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context Window | 200,000 tokens | 400,000 tokens |
| Agent Suitability | 92/100 | N/A |
| Time to First Token (TTFT) | 360 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-02-15 | 2026-02-24 |
API Pricing Comparison
Input Price per Million Tokens
Claude 3.5 Sonnet v2
$3.00
GPT-5.3-Codex
$1.75
Output Price per Million Tokens
Claude 3.5 Sonnet v2
$15.00
GPT-5.3-Codex
$14.00
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Claude 3.5 Sonnet v2 Quirks & Gotchas
- ▸Well-characterized production behavior — ideal for teams needing stability
- ▸Upgrade to Claude 4.6 Sonnet for 1M context and improved agentic performance
GPT-5.3-Codex Quirks & Gotchas
No developer gotchas reported.