Unreleased Claude Fable 5.5 Codes Its Own 66-Second Animation

Anthropic's unreleased flagship model Claude Fable 5.5 is drawing attention in developer communities. One 66-second animation clip shows the model ran code on its own for about 2 hours 40 minutes, with no image or video tools used. It made the visuals, music, and sound effects, all packed into one HTML file. Unlike Sora or Runway, which generate video directly, this demo builds animation entirely through code. In comparison tests, Fable 5.5 finished complex animated scenes in about an hour, while some current Claude models produced broken code or failed to run. Still, the tests lack a standard setting. Earlier, the model's name appeared in LiteLLM's catalog and in Anthropic's website source code. The timing comes as the company pushes toward its IPO. Its filing shows $33.24 billion in revenue for the first three quarters, but Anthropic has yet to confirm the new model's release or specs.