Flux
moonshotai/Kimi-K3

moonshotai/Kimi-K3

moonshotai/Kimi-K3 As promised earlier this month, Moonshot have released the weights for their excellent 2.8 trillion parameter Kimi K3. They're a hefty 1.56TB on Hugging Face. Kimi introduced their own janky modified version of the MIT license with K2 back in July 2025. That license just added this paragraph requiring attribution beyond a certain size of commercial entity: Our only modification part is that, if the Software (or any derivative works thereof) is used for any of your commercial…

Simon Willison's Weblog
An opinionated guide to which AI to use to do stuff

An opinionated guide to which AI to use to do stuff

An opinionated guide to which AI to use to do stuff It's interesting watching the evolution of Ethan Mollick's guide over time. A year ago it was still all about chat - ChatGPT, Claude, Gemini - with o3, Claude 4 Opus, and Gemini 2.5 Pro as the models and Deep Research as a useful alternative mode. Today it's much more about agentic systems - "where the AI is capable of doing the equivalent of many hours of real human work in one go". Gemini has fallen off Ethan's list, since Google still…

Simon Willison's Weblog
An Inside Look at the Relay Market Powering Token Resellers and Fraud

An Inside Look at the Relay Market Powering Token Resellers and Fraud

An Inside Look at the Relay Market Powering Token Resellers and Fraud Fascinating investigation by Matt Lenhard into the market that has grown up around reselling LLM tokens at a discount by pooling API keys from various sources. This looks to be mostly a thing in China. Resellers sell access to an LLM proxy that offers significant discounts on regular API pricing, which they achieve by abusing free trials, proxying through unprotected support bots, or sometimes through stolen credit cards or…

Simon Willison's Weblog
Teaching LLMs to Update Beliefs for Efficient Long-Horizon Interaction

Teaching LLMs to Update Beliefs for Efficient Long-Horizon Interaction

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BAIR Blog
Ruff v0.16.0

Ruff v0.16.0

Ruff v0.16.0 Astral shipped a significant new version of their Ruff Python linting tool a few days ago on July 23rd. I noticed today because my various CI jobs all started failing thanks to new default Ruff checks and my unpinned "ruff" dev dependency. From Brent Westbrook's announcement post: Ruff now enables 413 rules by default, up from 59 in previous versions. Since Ruff's default rule set was last modified in v0.1.0, the number of rules in Ruff has grown from 708 to 968. Many of these…

Simon Willison's Weblog
Quoting Boris Cherny

Quoting Boris Cherny

More than any of these eval scores, what is most exciting to me is something else: Opus 5 is our least prompt injectable model yet. It is a bit buried in the system card, but across PI evals and red teaming, Opus 5 is very hard to prompt inject successfully. — Boris Cherny, here's that System Card section, page 73 Tags: prompt-injection, anthropic, claude, generative-ai, ai, llms, boris-cherny

Simon Willison's Weblog
Introducing Claude Opus 5

Introducing Claude Opus 5

Introducing Claude Opus 5 I've been offline kayaking with sea otters for much of today so I haven't had a chance to put Anthropic's new model Claude Opus 5 through its paces yet. The buzz is positive, and Anthropic's description of it as a "thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price" sounds promising. It's currently leading the Artificial Analysis leaderboard, in front of even Fable 5. It's priced the same as Opus 4.8, and…

Simon Willison's Weblog
The Economics of Agentic AI: Engineering for Imperfection

The Economics of Agentic AI: Engineering for Imperfection

The price of adoption euphoria You played entirely by the book. You procured the most capable enterprise models, mandated adoption across your teams, and put the right metrics in place. The promise was a predictable boost in efficiency. And at first, it delivered. The demos were flawless. The prototypes worked. The agents reasoned with a […]

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