Tencent has released and open-sourced Hy4 preview, the newest flagship large language model from its Hunyuan team, adding another heavyweight to China’s crowded open-weight race, the company said in an announcement published August 28.
A 770-billion-parameter model, fully open
Hy4 preview uses a Mixture of experts design with 770 billion total parameters, of which only 49 billion activate for any given token, according to Tencent. The model ships with a context window exceeding 1 million tokens and is released under an unrestricted Apache 2.0 license as part of the broader push toward permissive open-source AI licensing, permitting commercial use, modification and redistribution without a separate agreement. Full weights, roughly 1.56 terabytes, are posted on Hugging Face alongside a cheaper-to-run FP8 quantized variant.
Tencent says Hy4 preview was co-designed with its CodeBuddy and WorkBuddy productivity tools and trained on work data from software engineers, game developers, finance analysts and security professionals. The company said the model can “generate a playable prototype from a single natural-language request, and work effectively with game engines.”
Tencent says the model helped train itself
In a notable detail, Tencent said Hy4 preview was used to optimize parts of its own training and inference pipeline, increasing end-to-end throughput by 31.8% against a baseline — an early example of a large model contributing directly to its own successor’s development.
On an internal blind evaluation Tencent ran across 163 experts and 203 engineering tasks, the company reported Hy4 preview scoring 2.99 out of 4.00, narrowly ahead of Moonshot AI’s Kimi K3 (2.94) and Zhipu’s GLM-5.3 (2.92). Because Tencent ran and reported the comparison itself, the figures invite independent verification.
Part of a broader race
The release follows a summer of rapid open-weight launches from Chinese labs, including Alibaba’s Qwen3.8-Flash-Next preview of its next-generation architecture. Hy4 preview is accessible through Tencent’s own Yuanbao and ima apps, with free access on WorkBuddy and CodeBuddy for the first two weeks after launch. API access runs through Tencent Cloud TokenHub and OpenRouter, priced as of August 2026 at $0.834 per million input tokens and $2.501 per million output tokens, with cache hits at $0.042 per million tokens.