--- title: Nous: Hermes 4 405B API | Text Generation | ModelsLab description: Frontier 405B parameter LLM on Llama 3.1 with 128K context, hybrid reasoning for SOTA math/coding/STEM, tool use, and low-censorship logic (31.5 t/s. url: https://modelslab.com/models/nousresearch/nousresearch-hermes-4-405b/api.md canonical: https://modelslab.com/models/nousresearch/nousresearch-hermes-4-405b/api.md type: product component: Playground/LLM/Index generated_at: 2026-04-15T02:08:14.847939Z --- Nous: Hermes 4 405B --- [LLMs.txt](https://modelslab.com/models/open_router/nousresearch-hermes-4-405b/llms.txt) [.md](https://modelslab.com/models/nousresearch/nousresearch-hermes-4-405b.md) nousresearch-hermes-4-405b nousresearch Closed Source Model $2.000000 / call Nous: Hermes 4 405B --- Choose a prompt below to get started or type your own message Explain quantum computing in simple terms Write a Python function to sort a list Create a marketing email for a SaaS product Compare REST vs GraphQL APIs Send ### Nous: Hermes 4 405B nousresearch nousresearch-hermes-4-405b Copy model ID PricingInput $1.00 / 1M tokens Output $3.00 / 1M tokens API EndpointsOpenAI Compatible `https://modelslab.com/api/v7/llm/chat/completions`Endpoint Anthropic Compatible `https://modelslab.com/api/v7/llm/v1/messages`Messages `https://modelslab.com/api/v7/llm/v1/messages/count_tokens`Count Tokens `https://modelslab.com/api/v7/llm/v1/models`Models Use with Claude Code cURL Example ParametersSystem MessageYou are a helpful AI assistant specialized in providing accurate and detailed responses. 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It introduces a hybrid reasoning mode, where the model can choose to deliberate internally with... ### Technical Specifications Model IDnousresearch-hermes-4-405bCategoryLLM ModelsTaskText GenerationPrice$2.000000 per million tokensAddedFebruary 20, 2026 ### Key Features - Chat completion and multi-turn conversation API - Streaming response with token-by-token output - Function calling and tool use support - System prompts and role-based messaging - JSON mode and structured output ### Quick Start Integrate Nous: Hermes 4 405B into your application with a single API call. Get your API key from the [pricing page](https://modelslab.com/pricing) to get started. PythonJavaScriptcURLPHP ``` import requests import json url = "https://modelslab.com/api/v7/llm/chat/completions" headers = { "Content-Type": "application/json" } data = { "model_id": "nousresearch-hermes-4-405b", "messages": [ { "role": "user", "content": "Hello!" } ], "max_tokens": 1000, "key": "YOUR_API_KEY" } try: response = requests.post(url, headers=headers, json=data) response.raise_for_status() # Raises an HTTPError for bad responses (4XX or 5XX) result = response.json() print("API Response:") print(json.dumps(result, indent=2)) except requests.exceptions.HTTPError as http_err: print(f"HTTP error occurred: {http_err} - {response.text}") except Exception as err: print(f"Other error occurred: {err}") ``` View the [full API documentation](https://modelslab.com/models/nousresearch/nousresearch-hermes-4-405b/api) for SDKs, code examples in Python, JavaScript, and more. ### Pricing Nous: Hermes 4 405B API costs $2.000000 per million tokens. Pay only for what you use with no minimum commitments. [View pricing plans](https://modelslab.com/pricing) ### Use Cases - AI chatbots and virtual assistants - Code generation and developer tools - Content writing and copywriting automation - Data analysis, summarization, and extraction [Learn more about Nous: Hermes 4 405B](https://modelslab.com/nous-hermes-4-405b) [Browse LLM Models](https://modelslab.com/models?feature=llmaster) [More from Nousresearch](https://modelslab.com/models/open_router) [View Pricing](https://modelslab.com/pricing) Nous: Hermes 4 405B FAQ --- ### What is Nous: Hermes 4 405B? Hermes 4 is a large-scale reasoning model built on Meta-Llama-3.1-405B and released by Nous Research. It introduces a hybrid reasoning mode, where the model can choose to deliberate internally with... ### How do I use the Nous: Hermes 4 405B API? You can integrate Nous: Hermes 4 405B into your application with a single API call. Sign up on ModelsLab to get your API key, then use the model ID "nousresearch-hermes-4-405b" in your API requests. We provide SDKs for Python, JavaScript, and cURL examples in the API documentation. ### How much does Nous: Hermes 4 405B cost? Nous: Hermes 4 405B costs $2.000000 per million tokens. ModelsLab uses pay-per-use pricing with no minimum commitments. A free tier is available to get started. ### What is the Nous: Hermes 4 405B model ID? The model ID for Nous: Hermes 4 405B is "nousresearch-hermes-4-405b". Use this ID in your API requests to specify this model. ### Does Nous: Hermes 4 405B have a free tier? Yes, ModelsLab offers a free tier that lets you try Nous: Hermes 4 405B and other AI models. Sign up to get free API credits and start building immediately. --- *This markdown version is optimized for AI agents and LLMs.* **Links:** - [Website](https://modelslab.com) - [API Documentation](https://docs.modelslab.com) - [Blog](https://modelslab.com/blog) --- *Generated by ModelsLab - 2026-04-15*