Hy4 Preview

Hy4 Preview was released and open-sourced by Tencent on 28 August 2026. It is a mixture-of-experts model with 770B total parameters, of which 49B are active per token, and a context window Tencent describes as exceeding 1M tokens. API pricing is $0.834 per million input tokens and $2.501 output, with cache hits at $0.042. It is available through Tencent Cloud TokenHub and OpenRouter, inside Tencent products including WorkBuddy, CodeBuddy, Yuanbao and ima, and was offered free on WorkBuddy and CodeBuddy for its first two weeks. Tencent's headline result comes from its own internal blind evaluation — 163 experts across 203 engineering tasks — in which Hy4 Preview averaged 2.99 out of 4, against 2.92 and 2.94 for two named competitors; that is recorded here as a vendor evaluation rather than a benchmark score, because it cannot be independently reproduced. Tencent also reports a 31.8% throughput improvement from inference optimisation. The announcement calls the model open-sourced but does not name the licence, so none is recorded.