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Tencent HY4 Preview: A Powerful New Open-Weight AI Model

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Explore Tencent HY4 Preview, a massive open-weight AI model with strong coding, reasoning, agentic, and 3D development capabilities.<h2> </h2><h2>Tencent HY4 Preview: A Powerful New Open-Weight AI Model</h2>Tencent has released HY4 Preview, a massive new open-weight AI model that is attracting attention for its strong reasoning, coding, and agent capabilities. With 770 billion total parameters, but only around 49 billion active parameters at a time, HY4 is designed to deliver powerful performance without requiring every parameter to be processed for every request. It also comes with a huge 1 million-token context window, allowing it to work with extremely large amounts of information in a single task. <h2>Built for Complex AI Tasks</h2>HY4 is aimed at more demanding workloads rather than simple question-and-answer tasks. Its strengths include:<ul><li>Software engineering and debugging </li><li>Long-running agentic workflows </li><li>Document-heavy tasks </li><li>Scientific research </li><li>Reasoning </li><li>Financial and document analysis </li><li>Web and 3D development</li></ul> Its performance is particularly competitive in coding, reasoning, and AI-agent tasks. While it does not beat the leading models on every benchmark, it performs strongly against other major open-weight models. <h2>Impressive Coding and Game Development</h2>One of HY4's most interesting capabilities is its ability to build complex software and game prototypes from prompts. In one demonstration, HY4 created a playable Spider-Man-style game through multiple iterations. The project took around six hours and used approximately 5.6 million tokens, with the entire run costing about $13. It was also used to create 3D game experiences featuring environments, characters, animations, textures, menus, and gameplay mechanics. These demonstrations show that HY4 can go beyond generating small pieces of code and work toward much larger projects. <h2>HY4 vs Other Open Models</h2>HY4 performs particularly well when compared with models such as GLM 5.3 Flash, Qwen 3.8 Flash, and DeepSeek V4. In one comparison against GLM 5.3 Flash, the difference was relatively small. GLM still produced stronger visual depth in some areas, but HY4 delivered surprisingly competitive results. HY4 also performed strongly in 3D development tests. In an orbital-repair simulation, it maintained the logic of the scene more consistently while producing stronger lighting and camera work than the competing model tested. In an International Space Station simulation, HY4 produced the strongest final result among the four open models tested. However, it was not the cheapest or fastest option in that particular test. <h2>A Huge Model That Can Be Compressed</h2>HY4's original model size is enormous, but its weights can be compressed significantly. The model was reduced from roughly 1.5 TB to around 200 GB through quantization, while benchmark performance reportedly changed very little. This makes the model considerably more practical for people who want to experiment with it locally, although the hardware requirements are still substantial. The open weights are available in lower-quantized versions, while users can also access HY4 through Tencent's cloud API. <h2>Competitive Pricing</h2>HY4 also stands out because of its pricing. With a 1 million-token context window, the reported API pricing is approximately $0.83 per million input tokens and $2.50 per million output tokens. This makes it an attractive option for developers who need a powerful model while keeping costs relatively low. <h2>Is HY4 the Best Open-Weight Model?</h2>HY4 is clearly one of the most impressive open-weight models in several areas, especially reasoning, coding, agentic tasks, and complex web or 3D development. However, it is not automatically the best model for every situation. Other models can offer better visual design, lower costs, faster generation, or different strengths depending on the task. The biggest advantage of HY4 is its combination of high-end capabilities, open weights, a huge context window, and relatively competitive pricing. For developers and AI enthusiasts looking for an open-weight model capable of handling serious projects, HY4 Preview is definitely a model worth testing.