Anthropic has increased free access to its Claude Fable 5 AI model for subscribers, marking the second extension within a week. This move closely follows OpenAI’s launch of GPT-5, which includes the new flagship model, Sol, touted for its advanced performance in coding, cybersecurity, and scientific tasks.
Claude Fable 5 will remain available at no additional cost to subscribers through mid-July, allowing users to allocate up to half of their weekly subscription usage to the model, a policy first put in place with an earlier promotional extension. After exceeding this limit, users can continue accessing the model by purchasing usage credits, enabling flexible pay-as-you-go use.
OpenAI has publicly claimed that Sol outperforms Anthropic’s Fable in coding and specialized scientific queries. Specifically, OpenAI highlighted that Fable reverts to an older model version when responding to biology and chemistry questions, potentially limiting its capabilities in these fields. Anthropic acknowledges this fallback mechanism as part of its current approach to managing more complex scientific requests.
Anthropic’s flagship model, Mythos, underlies Fable but incorporates additional safety filters. Mythos remains in limited release, currently accessible only to about 150 organizations across more than a dozen countries. The company confirmed plans for broader public availability in the future but noted that Mythos’s initial deployment focused on cybersecurity applications. Its ability to identify and exploit software vulnerabilities reportedly surpasses all but the most expert human hackers, underlining its potential for both defense and offensive security tasks.
The rivalry between Anthropic and OpenAI has intensified recently, with public critiques exchanged between leaders of both companies. Anthropic’s CEO, a former OpenAI executive, expressed doubts about OpenAI’s leadership and vision, while OpenAI’s CEO accused Anthropic of dishonesty in its advertising strategies. These tensions reflect growing competition over dominance in advanced AI development and commercial adoption.