Anthropic's upgraded Mythos-class flagship, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work.
OpenAI's high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads.
No shared demos for these models yet.
No captured outputs for these models yet.
Both Claude Fable 5.1 and GPT 5.5 Pro 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 Fable 5.1 has a lower blended cost. Claude Fable 5.1: $10.00 input / $50.00 output. GPT 5.5 Pro: $30.00 input / $180.00 output.
GPT 5.5 Pro has a larger context window: Claude Fable 5.1 supports 1M tokens vs GPT 5.5 Pro at 1.1M tokens.
Yes, both Claude Fable 5.1 and GPT 5.5 Pro support vision/image input.
Key differences: Claude Fable 5.1 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 Claude Fable 5.1 and GPT 5.5 Pro for free on idapt.app to see which performs better for your specific needs.