Hy4 preview

Hy4 Preview is Tencent Hunyuan’s next-generation open-source Mixture-of-Experts flagship model. Also known as Tencent Hy4 Preview or Hunyuan 4 Preview, it has 770B total parameters, activates 49B parameters per token, and supports a context window exceeding 1M tokens. It is designed for coding, office work, scientific research, reasoning, and complex agent workflows.

Hy4 Preview is well suited to large-repository coding, software planning and debugging, long-document analysis, multi-file office tasks, scientific research, tool-using agents, and workflows that must preserve context across many steps. Its productivity focus makes it most relevant when a task requires sustained execution rather than a single short response.

Its main strengths are long-context understanding, multi-step planning, coding, tool use, debugging, validation, and sustained agent execution. The sparse MoE architecture provides much more total model capacity than the number of parameters activated for each token, while the open weights make deployment and technical evaluation possible outside a single hosted product.

Hy4 Preview is an early release rather than the final Hy4 model, so behavior, availability, pricing, and integration details may change. Teams should regression-test important workflows, review tool actions, monitor long reasoning traces, and keep a fallback model for production systems. Large open-weight deployments also require substantial serving resources.

Use the Hy4 Preview model ID displayed in the TokenHub catalog with your TokenHub endpoint and API key. Follow the selected endpoint’s format for messages, reasoning options, streaming, tools, and structured output. If you are migrating from a Tencent Hunyuan API integration, validate request fields, tool schemas, and response parsing before moving production traffic.

Check the current TokenHub model page for input, output, cache, or request-based pricing and supported endpoints. Estimate cost with your real prompt length, expected output, reasoning behavior, concurrency, tool calls, and retry rate. Because this is a preview model, avoid treating launch pricing or temporary availability as a permanent service commitment.

Evaluate Hy4 Preview first when you need much longer context, stronger multi-step execution, large-scale coding, document-heavy work, or scientific research. Hy3 may be the safer choice when an existing production workflow already depends on its tested behavior, latency, or integration contract. Run both models on the same representative tasks before migrating.