Kimi K3 is the biggest open AI model ever built — and it puts China one step behind America's best
China's Moonshot AI released Kimi K3, a 2.8-trillion-parameter open-weight model that beats GPT-5.5 and Claude Opus on several benchmarks. Asian AI stocks shook.
It’s called Kimi K3, it has 2.8 trillion parameters, and according to Moonshot AI it’s the largest open-weight AI model ever published. The Beijing startup dropped it this week with carefully staged timing — days before the World AI Conference in Shanghai — and the numbers explain the noise: on benchmark tests, K3 goes toe to toe with the most powerful closed systems the United States has to offer.
In the published benchmarks, the model beats Anthropic’s Claude Opus 4.8 and OpenAI’s GPT-5.5 in areas like coding and agentic tasks, trailing only the very latest top-tier versions from both houses. In blind tests with developers, there were even categories — front-end code among them — where K3 came out as the favourite across every model tested. All of it with a one-million-token context window, native text and image support, and open weights, with full publication promised later this month on Moonshot’s site.
What is Kimi K3 and why does it matter?
It’s China’s strongest answer yet in the AI race: an open model at the technological frontier, published for free while American rivals charge for access to their best systems. For developers and companies — Portuguese ones included — it means running a near-frontier model without paying licence fees; for the US labs, it means the edge they sell just shrank again.
Markets got the message instantly: shares of Chinese rivals plunged in Hong Kong — Z.ai lost as much as 30% and MiniMax 16% — and the jitters spread through a global tech sector already uneasy about AI valuations. When a newcomer gives away what others sell dearly, the whole board shakes.
The question left hanging is the usual one in this race: how long does anyone’s lead actually last? Judging by 2026, the answer is measured in weeks.
By Oliver Grant
Image: Software: Moonshot AIScreenshot: VulcanSphere / Wikimedia Commons (public domain)
