The US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees. The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Claude models is not affected. We apologize for this disruption to our customers. We believe this is a misunderstanding and are working to restore access as soon as possible. Read our full statement: anthropic.com/news/fable-myt…

Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use. Its capabilities exceed those of any model we’ve ever made generally available.

This is a super exciting release - Claude Fable 5 is the same underlying model as Mythos but with added safeguards. The benchmarks are great and it's SOTA on everything by a margin but I'll add that *qualitatively* also, this is a major-version-bump-deserving step change forward (imo of the same order as Claude 4.5 was in November), peaking especially for long problem-solving sessions on very difficult problems. You can give it a lot more ambitious tasks than what you're used to, the model "gets it" and it will just go, and it's never felt this tempting to stop looking at the code at all (but don't do this in prod!). The model still has quirks that people will run into and the safeguards are configured to be a little too trigger happy for launch, which can hopefully be tuned over time. I feel a lot of things changing as working software increasingly comes out on a tap. The Jevon's paradox kicks in and I feel my own demand for software growing substantially. You can ask for anything - explainers, visualizers, dashboards, bespoke single-use apps (e.g. a full wandb that is hyper-specific just for your project), you can 10X your test suite, auto-optimize code, run giant research projects with custom HTML for the results, anything! "Free your mind" (Matrix ref). Really looking forward to all the things people build!

The /effort Ultracode design is simply fabulous. 🔥🔥 @bcherny @trq212 @sidbid

Introducing Claude Opus 4.8: it builds on Opus 4.7 with sharper judgment, more honesty about its own progress, and the ability to work independently for longer than its predecessors. Available today at the same price.

This was the most awe inspiring thing I’ve ever seen. The future will be wildly better than today.

And then… The DEVIL WAS BORN. #DragonGlimpse Telugu - youtu.be/bedocP4nRAo Hindi - youtu.be/DZ9lpup4VZ0 Tamil - youtu.be/3bxrl9k-kn4 Kannada - youtu.be/y0jHSknxFaw Malayalam - youtu.be/X5Ytvu0gxAA #Dragon @AnilKapoor #PrashanthNeel @rukminitweets #BijuMenon @ravibasrur @MythriOfficial @NTRArtsOfficial @DragonMovieOffl @TSeries

the future is bright, lets get to work

HUGE!!

Personal update: I've joined Anthropic. I think the next few years at the frontier of LLMs will be especially formative. I am very excited to join the team here and get back to R&D. I remain deeply passionate about education and plan to resume my work on it in time.

HTML continues to be undefeated

When do you reach for other models instead of Claude? What can we do better? Hit me with all of your frustrations. dms open. If you can give me detail (e.g. specifics/transcipts) - it'll help a lot in finding out exactly what we need to do to improve the next model

Happy Friday! We've reset everyone's 5-hour and weekly rate limits.

First in my bloodline to see 1 million line change PR getting merged (Bun's master branch is now rust, it's official)

Bun Rewrite in Rust is Merged

Say what you want: this is impressive. github.com/oven-sh/bun/pull/…

Thank you to the entire Claude team for an incredible Code with Claude event! Special shoutout to @bcherny, @trq212 , @_catwu, @katelyn_lesse and the team for the inspiring keynote, live coding sessions, and the generous 3 months of Claude Max offer. The energy, transparency, and real-world insights were top-tier. Huge thanks to @bcherny (and the full team) for building something this special. Keep pushing the frontier! 🙌 #Claude #CodeWithClaude #Anthropic

How do you keep Claude working until the job is done? Claude Code helps with this in a few ways, including one we shipped recently: /goal.

HTML is the new markdown. I've stopped writing markdown files for almost everything and switched to using Claude Code to generate HTML for me. This is why.

New in Claude Code: agent view. One list of all your sessions, available today as a research preview.