NMI Authentication API
The Authorization endpoint allows clients to securely authenticate and obtain an access token for making requests to the API.
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OpenAPI Specification
openapi: 3.2.0
info:
title: Payments Sign-Up Authentication API
description: Payments Sign-Up API
version: 1.0.0
license:
name: Proprietary
url: https://api.nmipayments.com/license
servers:
- url: https://sandbox.signup.nmi.com/api/v1
description: Sandbox
- url: https://secure.nmi.com/api/v5/signup
description: Production
tags:
- name: Authentication
description: The Authorization endpoint allows clients to securely authenticate and obtain an access token for making requests to the API.
paths:
/oauth/token:
post:
tags:
- Authentication
security: []
summary: Request an Access Token
description: 'This endpoint issues an OAuth access token via an HTTP POST request. The token remains valid for 60 minutes.
After expiration, you must request a new token.
### Available Scopes and their access
| Scope | Description |
|---|---|
| packages:read | Read packages information |
| applications:read | Read access to applications |
| applications:write | Write access to applications |
| subscriptions:read | Read access to subscriptions |
| subscriptions:write | Write access to subscriptions (subscribe/updated/delete) |'
operationId: getAccessToken
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
grant_type:
type: string
description: The OAuth2 grant type (e.g., `client_credentials`).
enum:
- client_credentials
client_id:
type: string
description: Client Key identifier
maxLength: 100
client_secret:
type: string
description: Client Secret
maxLength: 100
scope:
$ref: '#/components/schemas/scope-types'
required:
- grant_type
- client_id
- client_secret
examples:
success:
summary: Success
description: Request an Access Token for a Client
value:
grant_type: client_credentials
client_id: '**********'
client_secret: '**********'
scope: '*'
failure:
summary: Client Authentication Failed
description: Request an Access Token using an invalid Client
value:
grant_type: client_credentials
client_id: invalid_data
client_secret: invalid_data
scope: '*'
responses:
'200':
description: Successful response with the Access Token
content:
application/json:
schema:
type: object
required:
- access_token
- token_type
- expires_in
properties:
token_type:
type: string
description: The type of token (typically `Bearer`).
maxLength: 100
expires_in:
type: integer
description: The lifetime of the token in seconds.
example: 3600
access_token:
type: string
description: The access token used to authenticate requests to protected resources.
maxLength: 10000
examples:
success:
summary: Success
description: The response contains an access token.
value:
token_type: Bearer
expires_in: 3600
access_token: eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJhdWQiOiI5ZDdhZDgwNS00NzZjLTQ0OTAtOWVkYS0yNzYzNDkxNTRkNzkiLCJqdGkiOiJmYjhjNjcwODcyMjkwMjhmZTcyYzcwMTVmMTNjZmY2Mjc4YzA3ODI5NmU5YWZiYjUwZGZiY2E1NGQzNzFmOWJjZjNmMjQ4NmRiNTMyMzhjMCIsImlhdCI6MTczMTY4MzIzMS44MDg3MTUsIm5iZiI6MTczMTY4MzIzMS44MDg3MTksImV4cCI6MTc2MzIxOTIzMS43NzAyMDgsInN1YiI6IiIsInNjb3BlcyI6WyIqIl19.jwquLMGyVVttPEC4Sa0TgKqOniUc2xS1JKG9qYdJxn2BdevAI87IfkZDwqoNkjuJCFNJF21MKkratf8xJtzyni-SK43UyYQ5uExMbYRCxFfRdPfn2siFokS8jE4vakAFVbUgxPFpGT83MGjX2QAZ-P1fL_DxT7b7xSxK3hxl_npumQyZSsqgx79N3g5xCDs6BpbtPonOVbG1exjVMoWt3H492j9A8p99OUuLTho1IYF47Gk3NBlEEYSYa2I2NIhETIEjxOeo4BkW1i0IyV3Kz1Ai_uqT0u_iCepI0P-6QySLs9hsWaKxvH9F-mpe5EqpDdz_WTB5EWq2vhg8EbfQjzKLSeBzFvuQp9CWYjjHgGDCgGPicQtbAa6zFlOsLQ9GA2xXlR5N7ikpGphrWSHmGxdJF3q57RLfRK8QW2EIB0WvoumER0apBG5d-ma_xxacLDJtwCWd7jF7oKPvDAzU1NZsaH3plDFGpHZQCTsRT1_Mz3FSxTV-42Hn1rhCrhGtHHxQtSb96t__3Jbj4qPNhlqXeboi0-ZXDtiO0LbPp2wnl3_UxaR0w-KVxbCYvtweb-SIT7lmnkZp1xxvJR-jCLZi6-_qyOUCK7ZXlibWC0CA7n_qLhSv8CXu1vw70nltqpnzXmO1Z063f5CIvdNjkl7mx1bOgO0NZk4hbb6cffY
'401':
description: Unauthorized
content:
application/json:
schema:
type: object
properties:
error:
type: string
description: The error type (e.g., `invalid_request`, `invalid_client`, `invalid_grant`).
maxLength: 100
error_description:
type: string
description: A detailed description of the error.
maxLength: 1000
message:
type: string
description: A message error.
maxLength: 255
examples:
failure:
summary: Client Authentication Failed
description: The invalid client response
value:
error: invalid_client
error_description: Client authentication failed
message: Client authentication failed
components:
schemas:
scope-types:
oneOf:
- type: string
enum:
- '*'
description: Accepts "*" to represent all scopes
- type: array
minItems: 1
maxItems: 10
uniqueItems: true
items:
type: string
enum:
- packages:read
- applications:read
- applications:write
- subscriptions:read
- subscriptions:write
description: Accepts an array of specific scopes
securitySchemes:
oauth:
type: oauth2
flows:
clientCredentials:
tokenUrl: /oauth/token
scopes:
'*': Full access
packages:read: Read packages information
applications:read: Read access to applications
applications:write: Write access to applications
subscriptions:read: Read access to subscriptions
subscriptions:write: Write access to subscriptions (subscribe/updated/delete)
x-provenance:
method: searched
source: https://docs.nmi.com/reference
harvested: '2026-10-14'
tool: harvest-readme-openapi.py
note: Assembled verbatim from the OpenAPI definition ReadMe embeds in each operation page of the provider's developer portal; paths and components merged by API title, nothing authored.
assembled_from:
- https://docs.nmi.com/reference/createapplication.md
- https://docs.nmi.com/reference/createsubscription.md
- https://docs.nmi.com/reference/deletesubscription.md
- https://docs.nmi.com/reference/getaccesstoken.md
- https://docs.nmi.com/reference/getapplication.md
- https://docs.nmi.com/reference/getapplicationdownloadagreement.md
- https://docs.nmi.com/reference/getapplicationlegalconsent.md
- https://docs.nmi.com/reference/getapplications.md
- https://docs.nmi.com/reference/getpackagebyid.md
- https://docs.nmi.com/reference/getpackages.md
- https://docs.nmi.com/reference/getsubscription.md
- https://docs.nmi.com/reference/getsubscriptions.md
- https://docs.nmi.com/reference/submitapplication.md
- https://docs.nmi.com/reference/updateapplication.md
- https://docs.nmi.com/reference/updateapplicationinfo.md
- https://docs.nmi.com/reference/updatesubscription.md
- https://docs.nmi.com/reference/uploaddocument.md
merge:
pages: 17
deduped: 353
conflicts_kept_first: 0