Kimi K3.1 Pro launches with 2.8T open weights, narrowing closed AI gap

Moonshot AI launched Kimi K3.1 Pro, a 2.8 trillion parameter open-weights Mixture-of-Experts model with 104 billion active parameters and a 1-million-token context window. Independent benchmarks place the model fourth on the Intelligence Index with a score of 55, surpassing the Fable 5.1 model and ranking eighth in Code Arena. The release includes a Highspeed API offering 2-3x faster output, though at double the cost, and promises open-weight availability on November 4, 2026.