Nous Research Chat API
OpenAI-compatible chat completions.
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OpenAPI Specification
openapi: 3.2.0
info:
title: Nous Research Inference API (Nous Portal) Chat API
version: v1
description: 'OpenAI-compatible inference API served by Nous Research at https://inference-api.nousresearch.com/v1. Exposes a model catalog and a chat-completions endpoint aggregating Nous Research''s own Hermes models alongside a broad catalog of third-party open and frontier models (OpenRouter-style routing). Requests authenticate with a Nous Portal API key (Bearer token). The API additionally supports the x402 HTTP payment protocol: an un-authenticated request returns HTTP 402 with an `accepts` envelope describing an exact Solana USDC micropayment, enabling pay-per- request agentic access without a pre-provisioned account. This specification was DERIVED by probing the live public API (GET /v1/models returns 200 with the model catalog; POST /v1/chat/completions returns 402 with an x402 payment envelope when unauthenticated). Only endpoints observed on the live host are described here; other OpenAI- compatible routes may exist but were not verified.'
x-source: https://inference-api.nousresearch.com/v1
x-derived-by: api-evangelist enrichment pipeline (live probe)
servers:
- url: https://inference-api.nousresearch.com/v1
description: Nous Research inference API (production)
security:
- bearerAuth: []
tags:
- name: Chat
description: OpenAI-compatible chat completions.
paths:
/chat/completions:
post:
tags:
- Chat
operationId: createChatCompletion
summary: Create a chat completion
description: 'OpenAI-compatible chat completions. Provide a `model` id from GET /models and a `messages` array. Supports streaming via Server-Sent Events when `stream: true`. Authenticate with a Nous Portal API key as `Authorization: Bearer <key>`; alternatively an un-authenticated request returns HTTP 402 with an x402 Solana USDC payment envelope for pay-per-request access.'
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/ChatCompletionRequest'
responses:
'200':
description: The chat completion result (or an SSE stream when `stream` is true).
content:
application/json:
schema:
$ref: '#/components/schemas/ChatCompletion'
'400':
description: Malformed request.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'401':
description: Missing or invalid API key.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'402':
description: Payment required. Returned for un-authenticated requests; body is an x402 payment envelope describing the exact Solana USDC micropayment accepted for this request.
content:
application/json:
schema:
$ref: '#/components/schemas/X402PaymentRequired'
'429':
description: Rate limited.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
components:
schemas:
ChatCompletionRequest:
type: object
properties:
model:
type: string
description: A model id from GET /models.
example: nousresearch/hermes-4-405b
messages:
type: array
items:
$ref: '#/components/schemas/ChatMessage'
stream:
type: boolean
description: Stream the response as Server-Sent Events.
default: false
temperature:
type: number
max_tokens:
type: integer
top_p:
type: number
tools:
type: array
items:
type: object
required:
- model
- messages
X402PaymentRequired:
type: object
description: x402 payment envelope returned with HTTP 402.
properties:
x402Version:
type: integer
example: 1
accepts:
type: array
items:
type: object
properties:
scheme:
type: string
example: exact
network:
type: string
example: solana
maxAmountRequired:
type: string
resource:
type: string
description:
type: string
mimeType:
type: string
payTo:
type: string
maxTimeoutSeconds:
type: integer
asset:
type: string
description: Token mint (USDC on Solana).
error:
type: string
ChatMessage:
type: object
properties:
role:
type: string
enum:
- system
- user
- assistant
- tool
content:
type: string
required:
- role
- content
Error:
type: object
properties:
error:
type: object
properties:
message:
type: string
type:
type: string
code:
type: string
ChatCompletion:
type: object
properties:
id:
type: string
object:
type: string
example: chat.completion
created:
type: integer
model:
type: string
choices:
type: array
items:
type: object
properties:
index:
type: integer
message:
$ref: '#/components/schemas/ChatMessage'
finish_reason:
type: string
usage:
type: object
properties:
prompt_tokens:
type: integer
completion_tokens:
type: integer
total_tokens:
type: integer
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: 'Nous Portal API key supplied as: Authorization: Bearer <key>'