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Nous: Hermes 4 405BReasoning. Your way.

Try Nous: Hermes 4 405BAPI Documentation

Hybrid reasoning meets production speed

Toggleable Reasoning

Deep thinking on demand

Switch between instant responses and internal deliberation with think tags for complex problems.

Frontier Performance

Math, code, logic mastery

accuracy on reasoning benchmarks with 100% reliability across evaluations.

Massive Context

131K token window

Process long documents, codebases, and multi-turn conversations without truncation.

Examples

See what Nous: Hermes 4 405B can create

Copy any prompt below and try it yourself in the playground.

Mathematical Problem

“Solve this differential equation step-by-step: d²y/dx² + 4dy/dx + 3y = e^(-x). Show all work and reasoning.”

Code Optimization

“Review this Python function for performance bottlenecks and suggest optimizations with complexity analysis.”

Logic Puzzle

“Five people sit around a table. Given these constraints, determine who sits where and explain your reasoning.”

Technical Analysis

“Analyze this system architecture diagram and identify potential failure points and scalability issues.”

For Developers

A few lines of code.
Reasoning model. Three lines.

ModelsLab handles the infrastructure: fast inference, auto-scaling, and a developer-friendly API. No GPU management needed.

  • Serverless: scales to zero, scales to millions
  • Pay per token, no minimums
  • Python and JavaScript SDKs, plus REST API
API Documentation 
import requests


response = requests.post(
    "https://modelslab.com/api/v7/llm/chat/completions",
    json={
  "key": "YOUR_API_KEY",
  "prompt": "",
  "model_id": ""
}
)
print(response.json())

FAQ

Common questions about Nous: Hermes 4 405B

Read the docs

Hermes 4 405B is a frontier reasoning model built on Meta-Llama-3.1-405B with hybrid thinking capabilities. It combines toggleable deep reasoning with broad assistant utility, excelling in math, code, STEM, and logic tasks.

The model can choose to deliberate internally using think tags or respond directly. You control this behavior with a reasoning_enabled parameter, balancing speed versus depth based on your needs.

Hermes 4 405B supports a 131K token context window for both input and output, enabling processing of long documents and complex multi-turn conversations.

Yes. The model supports JSON mode, schema adherence, function calling, and tool use for reliable structured generation in production systems.

It achieves 100% accuracy on hallucination and ethics benchmarks, 99.5% on general knowledge, and 96.3% on math reasoning. It maintains 100% reliability across all evaluated benchmarks.

Yes. Hermes 4 is an open-weight model family developed entirely through open-source methodologies and pure post-training techniques without architectural modifications.

Ready to create?

Start generating with Nous: Hermes 4 405B on ModelsLab.

Try Nous: Hermes 4 405BAPI Documentation