hermes-4-405b
Hermes 4 405B is a large reasoning model from Nous Research built on Meta-Llama-3.1-405B, with a hybrid reasoning mode in which the model can choose to deliberate internally before answering.
Pricing: Input 240 credits / 1M tokens (≈ $1.20), Output 720 credits / 1M tokens (≈ $3.60).
Prices updated
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Hermes 4 405B API on ModelFold
Hermes 4 405B is a large reasoning model from Nous Research built on Meta-Llama-3.1-405B, with a hybrid reasoning mode in which the model can choose to deliberate internally before answering. Try Hermes 4 405B in the ModelFold Playground, then call it from your own code through an OpenAI-compatible chat completions API.
What Is the Hermes 4 405B API
Hermes 4 405B at a glance
Hermes 4 405B is a chat model from Nous Research. It accepts text as input and returns text, with a context window of up to 131K tokens.
Use it without hosting anything
On ModelFold you call Hermes 4 405B with a single API key — no model weights to download and no inference servers to run. The same key also works for the other chat, image, video and audio models on ModelFold.
Core Capabilities of Hermes 4 405B
Up to 131K tokens of context
Keep long conversations, large documents and sizeable code in a single request, so the model can reason over the full material instead of fragments.
Reasoning mode
Hermes 4 405B can produce reasoning before its final answer; in the Playground you can switch reasoning on or off to compare results.
Structured outputs
Ask for JSON that follows a schema (response_format), which makes extraction, classification and system integrations more reliable.
How to Use Hermes 4 405B on ModelFold
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Step 1: Try it in the Playground
Open the Playground at the top of this page, type a prompt and see how Hermes 4 405B responds before writing any code.
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Step 2: Create an API key
Sign in to ModelFold and create an API key in the console. Keep it secret and send it as a Bearer token.
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Step 3: Send a request
Call POST https://modelfold.ai/v1/chat/completions with "model": "hermes-4-405b" and your messages. Existing OpenAI-compatible SDKs work by changing the base URL and key.
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Step 4: Ship and monitor
Integrate the response into your product and check token usage and spend for every call in the console logs.
What You Can Build with Hermes 4 405B
Analysis and complex reasoning
Work through research questions, data interpretation, planning and other problems that need careful step-by-step reasoning.
Writing and content
Draft, edit and translate articles, emails, product copy and documentation in a consistent tone.
AI coding assistants
Generate, explain, debug and refactor code, review pull requests and work through multi-file changes in developer tools and IDE plugins.
Frequently Asked Questions
What is Hermes 4 405B?⌄
Hermes 4 405B is a large reasoning model from Nous Research built on Meta-Llama-3.1-405B, with a hybrid reasoning mode in which the model can choose to deliberate internally before answering.
Which inputs does Hermes 4 405B support?⌄
Hermes 4 405B accepts text and returns text. Through ModelFold you send text messages; documents attached in the Playground are converted to text.
How long is the context window of Hermes 4 405B?⌄
Up to 131K tokens, shared between your input and the model’s output.
Does Hermes 4 405B support function calling?⌄
Function calling is not listed for Hermes 4 405B; requests that include tools will be rejected. Use plain prompts or JSON output instead.
How is Hermes 4 405B billed on ModelFold?⌄
Pay as you go by tokens: input and output tokens are charged at the per-million-token prices shown on this page. There is no monthly fee, and failed requests are not charged.
How do I call Hermes 4 405B through the API?⌄
Send a POST request to https://modelfold.ai/v1/chat/completions with "model": "hermes-4-405b", using your ModelFold API key as the Bearer token.
| Input | 240 credits 1M tokens≈ $1.20 |
| Output | 720 credits 1M tokens≈ $3.60 |
Billed per token: input and output are priced separately, and thinking tokens count as output. The Playground charges exactly the same way.
Read API docs →AI Agents · Claude Code / Cursor / Trae →curl https://modelfold.ai/v1/chat/completions \
-H "Authorization: Bearer $MODELFOLD_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"hermes-4-405b","messages":[{"role":"user","content":"Hello"}]}'