Claude 3 Opus 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 Opus and GPT-5.3-Codex.
Claude 3 Opus
Claude 3 Opus is Anthropic's most powerful model from the first Claude 3 generation, engineered for deep analysis, comprehensive research, and demanding multi-step task execution. Released in March 2024, it represented the frontier of Anthropic's capabilities at the time, with a 200,000-token context window suitable for processing large documents, synthesizing diverse research sources, and generating expert-level written content. Priced at $15/MTok for input, Claude 3 Opus remains available for teams with specific requirements for Claude 3-generation behavior, though most use cases are better served by the improved Claude 4 series.
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 Opus | GPT-5.3-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context Window | 200,000 tokens | 400,000 tokens |
| Agent Suitability | N/A | N/A |
| Time to First Token (TTFT) | N/A | N/A |
| Deployment Model | N/A | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2024-03-04 | 2026-02-24 |
API Pricing Comparison
Input Price per Million Tokens
Claude 3 Opus
$15.00
GPT-5.3-Codex
$1.75
Output Price per Million Tokens
Claude 3 Opus
$75.00
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 Opus Quirks & Gotchas
No developer gotchas reported.
GPT-5.3-Codex Quirks & Gotchas
No developer gotchas reported.