Nousresearch modelsChat Completions model

nousresearch/hermes-4-405b

Name: Nous: Hermes 4 405B
Price: 1 USD
Availability: InStock
Author: Nousresearch

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 <think>...</think> tra...

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Prompt

131.1K max output

Input $1.00/M · Output $3.00/M

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API details and access

Model Details

ProviderNousresearch

TypeLlm

Model IDnousresearch/hermes-4-405b

Capabilities

InputText

OutputText

Context-

Max Output131,072

VisionNot supported

Function CallingNot supported

Access details

Chat Completions

Base URLhttps://api.sandbase.ai

API Endpoint/v1/chat/completions

{
  "model": "nousresearch/hermes-4-405b",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ],
  "max_tokens": 512
}

Pricing

Input$1.00 / 1M tokens

Output$3.00 / 1M tokens

Production endpoint

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

POSThttps://api.sandbase.ai/v1/chat/completions

Model IDnousresearch/hermes-4-405b

Input Schema

9 parameters · 1 required · 8 optional

Parameter	Type	Required	Description
`messages`	object[]	Required	—
`top_k`	integer	Optional	Min: 0
`top_p`	number	Optional	Min: 0 · Max: 1
`stream`	boolean	Optional	Default: false
`max_tokens`	integer	Optional	Max: 131072
`temperature`	number	Optional	Min: 0 · Max: 2 · Default: 1
`response_format`	object	Optional	—
`presence_penalty`	number	Optional	Min: -2 · Max: 2
`frequency_penalty`	number	Optional	Min: -2 · Max: 2

Output Schema

Field	Type	Description
`id`	string	Unique identifier for the completion
`object`	string	Object type, e.g. "chat.completion"
`model`	string	Model used for the completion
`choices`	array	List of completion choices
`choices[].message.content`	string	Generated text content
`choices[].finish_reason`	string	Reason the generation stopped
`usage.prompt_tokens`	integer	Number of tokens in the prompt
`usage.completion_tokens`	integer	Number of tokens in the completion
`usage.total_tokens`	integer	Total tokens used

Code Examples

Ready-to-run snippets

curl https://api.sandbase.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "nousresearch/hermes-4-405b",
    "messages": [{"role": "user", "content": "Hello"}],
    "temperature": 0.7,
    "max_tokens": 2048,
    "stream": true
  }'

← Back to Nous: Hermes 4 405B

Related Models

nousresearch/hermes-2-pro-llama-3-8bHermes 2 Pro is an upgraded, retrained version of Nous Hermes 2, consisting of an updated and cleaned version of the OpenHermes 2.5 Dataset, as well as a newly introduced Function Calling and JSON Mode dataset developed in-house.nousresearch/hermes-3-llama-3.1-405bHermes 3 is a generalist language model with many improvements over Hermes 2, including advanced agentic capabilities, much better roleplaying, reasoning, multi-turn conversation, long context coherence, and improvements across the board. Hermes 3 405B is a frontier-level, full-parameter finetune of the Llama-3.1 405B foundation model, focused on aligning LLMs to the user, with powerful steering capabilities and control given to the end user. The Hermes 3 series builds and expands on the Hermes 2 set of capabilities, including more powerful and reliable function calling and structured output capabilities, generalist assistant capabilities, and improved code generation skills. Hermes 3 is competitive, if not superior, to Llama-3.1 Instruct models at general capabilities, with varying strengths and weaknesses attributable between the two.nousresearch/hermes-3-llama-3.1-70bHermes 3 is a generalist language model with many improvements over [Hermes 2](/models/nousresearch/nous-hermes-2-mistral-7b-dpo), including advanced agentic capabilities, much better roleplaying, reasoning, multi-turn conversation, long context coherence, and improvements across the board. Hermes 3 70B is a competitive, if not superior finetune of the [Llama-3.1 70B foundation model](/models/meta-llama/llama-3.1-70b-instruct), focused on aligning LLMs to the user, with powerful steering capabilities and control given to the end user. The Hermes 3 series builds and expands on the Hermes 2 set of capabilities, including more powerful and reliable function calling and structured output capabilities, generalist assistant capabilities, and improved code generation skills.nousresearch/hermes-4-70bHermes 4 70B is a hybrid reasoning model from Nous Research, built on Meta-Llama-3.1-70B. It introduces the same hybrid mode as the larger 405B release, allowing the model to either respond directly or generate explicit <think>...</think> reasoning traces before answering. Users can control the reasoning behaviour with the `reasoning` `enabled` boolean. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#enable-reasoning-with-default-config) This 70B variant is trained with the expanded post-training corpus (~60B tokens) emphasizing verified reasoning data, leading to improvements in mathematics, coding, STEM, logic, and structured outputs while maintaining general assistant performance. It supports JSON mode, schema adherence, function calling, and tool use, and is designed for greater steerability with reduced refusal rates.