Introducing Kimi K3.1 Pro

What happened

Kimi K3.1 Pro launched on the Kimi API today, with Moonshot promising full model weights by Nov 4, 2026. Pricing is USD $2.00/million input tokens and $10/million output tokens; a Highspeed version offers 2-3x faster performance at twice the price, except for input token cache hits. Artificial Analysis scored it at 55, behind Claude Opus 5.5 at 58 and ahead of three models at 53; Simon Willison also tested SVG pelican generation at its low, medium, and max reasoning levels.

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The story so far

Moonshot AI released Kimi K3.1 Pro, which Artificial Analysis ranked fourth on its Intelligence Index with a score of 55, up 11 points from Kimi K3 and three points behind Claude Opus 5.5. Artificial Analysis said the reasoning model made large gains in agentic performance. The model is available through Kimi.ai, Kimi Work, Kimi Code, and the Kimi API. Simon Willison reported API pricing of $2.00 per million input tokens and $10 per million output tokens. Moonshot says its Highspeed variant runs two to three times faster; Willison reported that it costs twice as much, except for input token cache hits, which carry the same price as the standard version. The weights are not yet open. Willison reported that Moonshot promised to release the full model weights by November 4, 2026. Artificial Analysis said Kimi K3.1 Pro would lead open-weights models once published, a position that depends on the release and rankings remaining unchanged.