Claude Sonnet 4.5 is Anthropic’s most secure AI mannequin but

In Might, Anthropic introduced two new AI methods, Opus 4 and Sonnet 4. Now, lower than six months later, the corporate is introducing Sonnet 4.5, and calling it one of the best coding mannequin on the earth up to now. Anthropic’s foundation for that declare is a collection of benchmarks the place the brand new AI outperforms not solely its predecessor but additionally the dearer Opus 4.1 and competing methods, together with Google’s Gemini 2.5 Pro and GPT-5 from OpenAI. For example, in OSWorld, a collection that checks AI fashions on real-world laptop duties, Sonnet 4.5 set a document rating of 61.4 p.c, placing it 17 proportion factors above Opus 4.1. 

On the identical time, the brand new mannequin is able to autonomously engaged on multi-step tasks for greater than 30 hours, a major enchancment from the seven or so hours Opus 4 may preserve at launch. That is an essential milestone for the kind of agentic methods Anthropic needs to construct. 

Maybe extra importantly, the corporate claims Sonnet 4.5 is its most secure AI system up to now, with the mannequin having undergone “intensive” security coaching. That coaching interprets to a chatbot Anthropic says is “considerably” much less liable to “sycophancy, deception, power-seeking and the tendency to encourage delusional considering” — all potential mannequin traits which have landed OpenAI in hot water in recent months. On the identical time, Anthropic has strengthened Sonnet 4.5’s protections in opposition to immediate injection assaults. Because of the sophistication of the brand new mannequin, Anthropic is releasing Sonnet 4.5 beneath its AI Security Degree 3 framework, that means it comes with filters designed to forestall probably harmful outputs associated to prompts round chemical, organic and nuclear weapons.  

With in the present day’s announcement, Anthropic can be rolling out high quality of life enhancements throughout the Claude product stack. To begin, Claude Code, the corporate’s widespread coding agent, has a refreshed terminal interface, with a brand new characteristic known as checkpoints included. As you may in all probability guess from the identify, they help you save your progress and roll again to a earlier state if Claude writes some funky code that is not fairly working such as you imagined it will. File creation, which Anthropic began rolling out at the start of the month, is now accessible to all Professional customers, and if you happen to joined the waitlist Claude for Chrome, you can begin utilizing the extension in the present day.   

API pricing for Sonnet 4.5 stays at $3 per a million enter tokens and $15 for a similar quantity of output tokens. The discharge of Sonnet 4.5 caps off a powerful September for Anthropic. Simply someday after Microsoft added Claude models to Copilot 365 final week, OpenAI admitted its rival presents one of the best AI for work-related duties.