Anthropic's upgraded Mythos-class flagship, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work.
Fastest and cheapest model in the GPT-4.1 series for low-latency applications.
No shared demos for these models yet.
No captured outputs for these models yet.
Both Claude Fable 5.1 and GPT 4.1 Nano 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.
GPT 4.1 Nano has a lower blended cost. Claude Fable 5.1: $10.00 input / $50.00 output. GPT 4.1 Nano: $0.10 input / $0.40 output.
GPT 4.1 Nano has a larger context window: Claude Fable 5.1 supports 1M tokens vs GPT 4.1 Nano at 1M tokens.
Yes, both Claude Fable 5.1 and GPT 4.1 Nano support vision/image input.
Key differences: GPT 4.1 Nano is significantly cheaper; only Claude Fable 5.1 offers extended reasoning mode. 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 4.1 Nano for free on idapt.app to see which performs better for your specific needs.