Anthropic unveils new version of scaled-down “Haiku” model

On Wednesday, Anthropic released Claude Haiku 4.5, the latest version of its smallest model. It’s touted to offer similar performance to Sonnet 4 “at one-third the cost and more than twice the speed,” according to the company’s blog post.

Anthropic cites a variety of new benchmark results to support these performance claims. In the company’s tests, Haiku scored 73% in the validated SWE-Bench and 41% in the command-line focused Terminal-Bench. This is below Sonnet 4.5, but in all cases it was on par with Sonnet 4, GPT-5, and Gemini 2.5. Testing showed similar results for tool usage, computer usage, and visual reasoning benchmarks.

The new version of Haiku will be available immediately on all free Anthropic plans, and the company believes it is particularly attractive for free versions of AI products that can provide important functionality while minimizing server load. The lightweight nature of the model also means that it is easy to deploy multiple Haiku agents in parallel or in conjunction with more sophisticated models.

Anthropic CPO Mike Krieger said in a statement to the press that Haiku will enable new styles to be deployed for the first time in production. “It opens up a whole new category of what is possible with AI in production, with Sonnet handling complex plans and Haiku-powered subagents running fast,” Krieger said. “We’re giving people a complete agent toolbox, with each model having the right combination of intelligence, speed and cost for different parts of the job.”

The most immediate applications are likely to be delivered by software development tools, where cloaked code is already commonly used and where latency is often a critical factor. In a statement provided by Anthropic, Zencoder CEO Andrew Filev said the new version of Haiku “unlocks a whole new set of use cases.”

Haiku 4.5 was released after a series of high-profile releases from Anthropic. It was released just two weeks after the release of Sonnet 4.5 and two months after the release of Opus 4.1, both of which were hailed as state-of-the-art at the time of their release. The previous version of Haiku was released in October 2024.