Hermes 4 405B

Hermes 4 405B API

Hermes 4 405B is a state-of-the-art, hybrid reasoning language model developed by Nous Research, built on the foundation of Meta’s Llama-3.1-405B. It is designed for advanced reasoning, structured outputs, and flexible user control, making it a top choice for demanding AI applications in math, code, STEM, and logical reasoning tasks.

Technical Specifications

• Base Architecture: Built on Llama-3.1-405B, one of the largest open-weight transformer models.
• Parameter Count: 405 billion parameters.
• Training Data: Instruction-tuned with ~60 billion tokens of high-quality post-training data, with heavy emphasis on reasoning traces.

Performance Benchmarks

• Math & Logic: Outperforms previous Hermes models and rivals leading closed-source models in math, code, and logical reasoning tasks.​
• STEM & Creativity: Excels in scientific, technical, and creative writing, with improved format-faithful outputs.​
• General Assistant: Maintains broad utility for general-purpose tasks, with high coherence in multi-turn conversations.​
• Speed vs. Depth: Hybrid reasoning mode allows users to choose between fast direct responses and deeper deliberation with explicit reasoning traces.

Key Features

• Hybrid Reasoning Mode: Users can toggle between fast, direct responses and detailed, trace-based reasoning using the reasoning boolean flag.​​‍
• Steerability: Highly customizable, with improved alignment and lower refusal rates for user-directed tasks.​‍
• Large Context: Handles long documents and complex multi-step tasks.​

Hermes 4 405B API Pricing

• Input: $1.05
• Output: $3.15

Use Cases

• Advanced Reasoning: Ideal for math, logic, and STEM problem-solving.​
• Code Generation: Reliable for code synthesis, debugging, and technical documentation.​
• Creative Writing: Supports creative storytelling, roleplaying, and subjective responses.​
• Enterprise Integration: Suitable for enterprise assistants, chatbots, and workflow automation.

Code Sample

Comparison with Other Models

vs Llama-3.1 Instruct: Hermes 4 405B offers superior reasoning, structured outputs, and steerability, with a larger post-training corpus and hybrid reasoning mode.​

vs GPT-4.1 nano: Hermes 4 405B matches or exceeds GPT-4.1 nano in intelligence and reasoning, with a much larger context window and lower refusal rates.​

vs Hermes 3: Hermes 4 features a 50x larger training dataset, improved reasoning traces, and enhanced schema adherence and function calling.​

vs Claude 3: Hermes 4 405B excels in math, code, and structured outputs, with a focus on user control and neutrality.

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