US startup Anthropic on Monday announced the launch of its new generative artificial intelligence model, Claude Sonnet 4.5, which it says is the world’s best for computer programming.
Anthropic was created in early 2021 by former OpenAI staff who felt their employer, led by CEO Sam Altman, was not doing enough to control and prevent the potentially harmful effects of its models.
Backed by Amazon, it quickly joined the major players in generative AI that embarked on a frantic race after the arrival of ChatGPT from OpenAI in November 2022, with new models being released at a furious pace with ever-expanding capabilities.
While trailing OpenAI in terms of users and name recognition, Anthropic had been considered for several months the top performer in generative AI for computer coding.
This is seen as a highly strategic accomplishment, with programming often cited as the specialty most ripe for disruption — and revenue generation — by AI in the near term.
But OpenAI’s most recent assistant, GPT-5, launched in early August, had taken the lead in certain rankings for AI-generated programming, putting pressure on Anthropic to deliver more capability in its next offering.
In a key benchmark, Claude Sonnet 4.5, a new generation of language model, can operate autonomously for 30 hours straight once it is assigned a task.
This is a significant leap from Anthropic’s most powerful version until now, Claude 4 Opus, which could only run for seven hours.
These generative AI programs function alone for several hours as they regularly evaluate their own output and make changes and corrections autonomously.
Claude Sonnet 4.5 achieved the highest score when tested by the independent evaluation system SWE-Bench Verified, developed by researchers from Princeton and Stanford universities.
It is also, according to Anthropic, the most advanced model for developing AI agents capable of making real-world decisions for which they have not been trained or specifically programmed.
Anthropic’s new release is also the most sophisticated for applications that allow an AI assistant to use a computer as a human would.
Upon request in everyday language, the interface can perform a Google search or update a calendar.
This functionality was first offered by Anthropic in October 2024.
OpenAI launched an equivalent product, Operator, in January 2025.
