OpenAI's most advanced agentic coding model with 400K context.
Anthropic's Sonnet-class model for well-scoped everyday work, a direct upgrade over Claude Sonnet 5.
No shared demos for these models yet.
No captured outputs for these models yet.
Both GPT 5.3 Codex and Claude Sonnet 5.5 are capable AI models. The best choice depends on your specific use case: consider pricing, context window, speed, and which capabilities (vision, reasoning, audio) you need.
Claude Sonnet 5.5 has a lower blended cost. GPT 5.3 Codex: $1.75 input / $14.00 output. Claude Sonnet 5.5: $2.00 input / $10.00 output.
Claude Sonnet 5.5 has a larger context window: GPT 5.3 Codex supports 400K tokens vs Claude Sonnet 5.5 at 1M tokens.
Yes, both GPT 5.3 Codex and Claude Sonnet 5.5 support vision/image input.
GPT 5.3 Codex and Claude Sonnet 5.5 have similar overall capabilities. The main differences lie in pricing, context window size, and provider-specific strengths. Use this comparison page to review all metrics side by side.
If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both GPT 5.3 Codex and Claude Sonnet 5.5 for free on idapt.app to see which performs better for your specific needs.