OpenAI's high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads.
Anthropic's Mythos-class flagship for ambitious, long-running professional work.
No shared demos for these models yet.
No captured outputs for these models yet.
Based on the Capability Index, GPT 5.5 Pro scores higher (91.8 vs 91.6). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.
Claude Fable 5 has a lower blended cost. GPT 5.5 Pro: $30.00 input / $180.00 output. Claude Fable 5: $10.00 input / $50.00 output.
GPT 5.5 Pro has a larger context window: GPT 5.5 Pro supports 1.1M tokens vs Claude Fable 5 at 1M tokens.
Yes, both GPT 5.5 Pro and Claude Fable 5 support vision/image input.
Key differences: Claude Fable 5 is significantly cheaper. Compare full specs on this page.
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 5.5 Pro and Claude Fable 5 for free on idapt.app to see which performs better for your specific needs.