OpenAI's GPT-6 Luna served in pro reasoning mode for the hardest problems.
Anthropic's upgraded Mythos-class flagship, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work.
No shared demos for these models yet.
No captured outputs for these models yet.
Both GPT 6 Luna Pro and Claude Fable 5.1 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 6 Luna Pro has a lower blended cost. GPT 6 Luna Pro: $0.10 input / $0.50 output. Claude Fable 5.1: $10.00 input / $50.00 output.
GPT 6 Luna Pro has a larger context window: GPT 6 Luna Pro supports 1.1M tokens vs Claude Fable 5.1 at 1M tokens.
Yes, both GPT 6 Luna Pro and Claude Fable 5.1 support vision/image input.
Key differences: GPT 6 Luna Pro 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 6 Luna Pro and Claude Fable 5.1 for free on idapt.app to see which performs better for your specific needs.