Claude Fable 5.5, GPT 6.2 Astra Could Be Right Around the Corner, Leaks Suggest
Hidden code on Anthropic’s website and an entry in a developer tool suggest the company is testing an unreleased Claude model called Fable 5.5, while OpenAI is reportedly A/B testing a new GPT 6.2 Astra.
Anthropic has not announced a new version of its Claude chatbot, but users on X have reported seeing outputs that look stronger than the current Claude Opus 5.5. These users believe the requests are being routed to an unreleased model called Fable 5.5.
The chatter began on October 1 when users posted screenshots of Claude still labeled Fable 5.1 beside outputs they said looked superior. On October 11, a leaker named Chetaslua wrote that Claude Opus 5.5 is routing to a new model, which could be Fable 5.5 or a new Opus model.
An AI developer named Shikhar tested the claim by asking Opus to create a complex 2D animation. The resulting animation, a Spider-Verse-style scene of a character on a city street swinging over rooftops, was made with Opus but displayed a quality that the developer said was superior to the model’s usual output.
Is this Fable 5.5? Saw posts that Opus is routed to Fable 5.5, so I decided to make a complex 2D animation with it.
The rumors gained more weight on October 13 when an automated update to LiteLLM, an open-source tool developers use to connect to AI providers, added an entry named "claude-fable-5.5". The entry copied its price and limits from Fable 5.1, and it was later removed.
On November 1, a user known as Chubby reported finding a "Mythos 5.5" label in the hidden HTML source code of Anthropic’s official website. The label appeared in an invisible headline and in the alt text of the logo, but the live page on Monday showed only Mythos 5.1, the version Anthropic released in September.
Mythos is a restricted model that Anthropic offers to a select group of clients, including government and cyber giants, due to its capabilities. Fable is the top commercial tier of Claude, the chatbot that competes with ChatGPT, and is the priciest flagship Anthropic sells for writing software and handling office work.
OpenAI’s GPT 6.2 Astra
OpenAI is also reportedly testing a new model, GPT 6.2 Astra. A user named TokenGremlin wrote on Sunday that the model is already showing up in Codex usage analytics, which track how developers use OpenAI’s coding assistant.
The model picker on OpenAI’s interface still says GPT 6 Astra, but the usage breakdown for some accounts now lists gpt-6.2-astra separately. A screenshot circulating on X showed gpt-6.2-astra at 19.8% of one account’s usage, next to gpt-6-astra at 80%.
OpenAI is quietly A/B testing a new variant called GPT-6.2 Astra, and it’s already showing up in Codex usage analytics.
The rumors about Fable 5.5 and GPT 6.2 Astra come as Anthropic prepares for its IPO, the first sale of its shares to the public. Anthropic filed for an IPO on October 26, reporting $16.29 billion in revenue for the first half of 2026 against $1.16 billion a year earlier.
Because Anthropic first filed confidentially in June, SEC rules require the paperwork to be public for 15 days before the roadshow, the marketing tour where banks pitch the shares to investors. This puts the earliest start at November 10.
Chubby, the user who found the Mythos 5.5 label, predicted a release of GPT 6.2 Astra "very soon, in response to Fable 5.5 and Anthropic’s IPO." He added, "Next week is going to be exciting."
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