Hy4

Hy4

Tencent
+
+

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About

Claude Fable 5.1 is Anthropic’s advanced AI model for coding, knowledge work, research, and long-running agentic tasks. It is designed to improve on Claude Fable 5 with stronger performance across software engineering, scientific research, multidisciplinary reasoning, computer use, business workflows, and complex problem solving. The model can handle extended multi-step work, verify its own results, diagnose difficult software issues, and operate effectively across tool-heavy workflows. Anthropic also reduced cache-read pricing for Fable 5.1, lowering typical usage costs compared with Fable 5 and creating larger savings for highly agentic workloads. Fable 5.1 includes updated safeguards intended to reduce false positives while allowing more legitimate cybersecurity tasks such as vulnerability discovery for defensive purposes. The model is available through Claude products, the Claude API, Amazon Web Services, Google Cloud, and Microsoft Azure.

About

Hy4 preview is a new-generation open source Mixture-of-Experts flagship model built for real-world productivity tasks across software engineering, office work, game development, and scientific research. The model contains 770B total parameters with 49B activated per token and supports a 1M-token context window, giving it the capacity to work through large codebases, extensive document collections, and long multi-step tasks. Its 78-layer architecture combines Gated DeepSeek Sparse Attention with IndexCache for cross-layer sparse index reuse and identity Hyper-Connections to expand information flow between layers. A native Multi-Token Prediction layer is included for speculative decoding. Hy4 preview is designed to understand, plan, debug, and verify long-horizon engineering tasks, with additional gains in front-end visual quality and interaction design.

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Audience

Software developers, researchers, enterprises, analysts, knowledge workers, and AI application teams that need advanced coding, reasoning, research, and long-running agentic capabilities

Audience

Developers, researchers, and technical professionals seeking an AI model for coding, document work, game development, scientific reasoning, and complex productivity tasks

Support

Phone Support
24/7 Live Support
Online

Support

Phone Support
24/7 Live Support
Online

API

Offers API

API

Offers API

Screenshots and Videos

Screenshots and Videos

Pricing

$10 per 1M tokens (input)
$10 per million input tokens and $50 per million output tokens
Free Version
Free Trial

Pricing

No information available.
Free Version
Free Trial

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Pros & Cons from Real Users

Pros

  • This feels like the model you reach for when the work is genuinely difficult. Not every task needs Fable, but for complex coding, long-horizon agents, deep research, and big messy knowledge-work projects, Fable 5.1 looks built for the hard stuff. The 1M-token context window is a huge advantage. For developers and AI power users, that means you can work across large repos, long docs, research sets, transcripts, spreadsheets, and project history without constantly chopping everything into pieces. I also like that Anthropic specifically calls out document, spreadsheet, and slide work. That makes it feel useful beyond coding alone — more like a high-end model for serious professional workflows.

Cons

  • The downside is price and complexity. Anthropic says most workloads should start with Claude Opus 5, and Fable 5.1 is better reserved for demanding reasoning or cases where Opus 5 still falls short.

Training

Documentation
Webinars
Live Online
In Person

Training

Documentation
Webinars
Live Online
In Person

Company Information

Anthropic
Founded: 2021
United States
claude.ai

Company Information

Tencent
Founded: 1998
China
hy.tencent.ai/research/hy4-preview

Alternatives

Alternatives

GPT-5.6 Sol

GPT-5.6 Sol

OpenAI
GPT-6 Astra

GPT-6 Astra

OpenAI
GPT-5.6 Sol

GPT-5.6 Sol

OpenAI
Claude Fable 5

Claude Fable 5

Anthropic
Claude Opus 5

Claude Opus 5

Anthropic
LongCat-2.0

LongCat-2.0

LongCat

Categories

Categories

Integrations

Aider
Anything
Bash
Bolt.new
C#
Claude Desktop
Claude Pro
Claude Security
Databricks
JavaScript
LaunchLemonade
Lua
Perplexity Computer
PrivatClaw
Snowflake Cortex AI
Springhub
Sup AI
TypeScript
Versuno
XML

Integrations

Aider
Anything
Bash
Bolt.new
C#
Claude Desktop
Claude Pro
Claude Security
Databricks
JavaScript
LaunchLemonade
Lua
Perplexity Computer
PrivatClaw
Snowflake Cortex AI
Springhub
Sup AI
TypeScript
Versuno
XML
Claim Claude Fable 5.1 and update features and information
Claim Claude Fable 5.1 and update features and information
Claim Hy4 and update features and information
Claim Hy4 and update features and information