Vibe Check: Anthropic Cooked on Claude Haiku 4.5

This one’s for the developers

Oct 15, 2025Updated Jun 3, 2026

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Anthropic just dropped Haiku 4.5—Anthropic’s newest “small” (aka least powerful, and cheapest—Claude model, and it’s great. We got our hands on it early and put it through its paces.

This is the story of the new Haiku, which just jumped version numbers from 3.5 to 4.5: It’s almost as powerful as the new Sonnet 4.5, faster, and much cheaper. And when I say almost as powerful, I mean it—I had a hard time telling the difference when testing it on complex queries like “given this P&L, analyze our Q3 performance.”

Here’s your day zero vibe check:

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