The largest set of model weights anybody can legally download and run is now Chinese, Apache 2.0, and was partly optimised by an earlier version of itself.

Hy4 preview has 770 billion total parameters with 49 billion active per token, 78 layers, 256 routed experts plus one shared, and a 1 million token context. Apache 2.0, with an FP8 build alongside it. The API price is $0.834 in and $2.501 out per million tokens.

Why this one is different

Two things. Apache 2.0 at this size is unusual: releases this large normally arrive under a bespoke licence with a revenue gate, as Alibaba's own Qwen3.8-Max did three weeks earlier. And Tencent report using the model during its own development to automate optimisation of the training method, and separately to optimise its inference infrastructure to a measured 31.8% throughput gain. That is a lab saying its model made the next model cheaper.

A lab saying its model made the next model cheaper.

How we got here

1. Jul 2026The Hy3 line, which Hy4 supersedes.
2. 3 Aug 2026Alibaba's Qwen3.8-Max opens its weights, but under a custom licence with a $50M revenue gate.
3. 28 Aug 2026Hy4 preview lands at 770B under Apache 2.0, with no revenue condition at all.

What it does and does not mean

Downloadable is not runnable. 770B parameters at 49B active still needs serious hardware to serve, so for most people this is an API with a licence attached rather than something they will host. The self-optimisation figure is also Tencent's own measurement of its own infrastructure, unreproduced by anyone. What is not in doubt is the licence: the largest open weights in the world now carry the most permissive terms in the category, and that is a deliberate competitive choice rather than an accident.