Anthropic ships Mythos 5 — and opens its weights

Anthropic released Mythos 5, its latest foundation model, and for the first time made the weights available under an open license. The company has been tightening access to Claude for years — a paid API, rate limits, and a waitlist for API keys. Now the model is out in the wild for anyone to run, fine-tune, or fork.

The release lands alongside a new open-source fund that Anthropic created to back independent researchers and toolmakers building on top of open weights. The fund isn't a venture fund; it's a grant pool. The goal is to keep the open ecosystem from being starved when Anthropic pulls its weights behind a paywall.

Why this matters for us: Open weights mean our local shops, our tías, and our side-hustlers can actually run these models on their own hardware instead of paying Anthropic's per-token rates to use someone else's.