Kimi K3.1 Pro came within a point of Claude Opus 5.5 on coding — weights go public Nov 4

Moonshot AI launched Kimi K3.1 Pro on October 23 — a heavily post-trained upgrade of its K3 model with a 1-million-token context window and a Highspeed variant that runs two to three times faster. Independent evaluator Artificial Analysis ranks it fourth on its Intelligence Index, just 3 points behind the top proprietary models.

Moonshot's own benchmarks put K3.1 Pro at 65.7% on Terminal-Bench 4.0 — ahead of GPT-6 Astra's 58.2% and within a point of Claude Opus 5.5's 66.4% — though those numbers are self-reported and unverified. The full model weights are promised for November 4, which would make it the highest-scoring open-weight model available.