> For the complete documentation index, see [llms.txt](https://docs.partssource.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.partssource.com/api/authentication/overview.md).

# Overview

Authenticate with the PartsSource APIs using OAuth 2.0

The PartsSource APIs use **JWT Bearer Token** authentication via **OAuth 2.0**. All API requests (except health checks) require a valid access token.

***

## Quick Start

### 1. Get an Access Token

```bash
curl -X POST https://auth.partssource.com/oauth2/token \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "grant_type=client_credentials" \
  -d "client_id=YOUR_CLIENT_ID" \
  -d "client_secret=YOUR_CLIENT_SECRET"
```

**Response:**

```json
{
  "access_token": "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...",
  "token_type": "Bearer",
  "expires_in": 3600
}
```

### 2. Use the Token

Include the token and API key in all requests:

```bash
curl -X GET "https://api.partssource.com/customer/api/users/lookup?userId=12345" \
  -H "Authorization: Bearer eyJhbGciOiJSUzI1NiIs..." \
  -H "x-api-key: YOUR_API_KEY"
```

***

## Authentication Flow

The APIs use the **OAuth 2.0 Client Credentials** flow, designed for machine-to-machine (M2M) integration:

```
Your Application                    Auth Server                      API
      |                                  |                            |
      |-- POST /oauth2/token ----------->|                            |
      |   (client_id, client_secret)     |                            |
      |                                  |                            |
      |<-- access_token -----------------|                            |
      |                                  |                            |
      |-- GET /api/resource ---------------------------------->|
      |   (Authorization: Bearer token)                        |
      |                                  |                            |
      |<-- Response -------------------------------------------|
```

***

## Token Details

| Property       | Value                 |
| -------------- | --------------------- |
| **Type**       | JWT (JSON Web Token)  |
| **Expiration** | 1 hour (3600 seconds) |
| **Algorithm**  | RS256                 |
| **Issuer**     | Authorization server  |

### Token Lifecycle

1. **Request** - Exchange credentials for access token
2. **Use** - Include token in API requests
3. **Refresh** - Request new token before expiration
4. **Expire** - Token becomes invalid after 1 hour

{% hint style="warning" %}
**Tokens expire after 1 hour.** Implement token refresh logic to avoid service interruption. See [Token Management](/api/authentication/oauth-2.0-flow/best-practices-and-error-handling.md) for best practices.
{% endhint %}

***

## Authentication Endpoints

| Endpoint      | URL                                                             | Purpose                          |
| ------------- | --------------------------------------------------------------- | -------------------------------- |
| **Token**     | `https://auth.partssource.com/oauth2/token`                     | Exchange credentials for token   |
| **JWKS**      | `https://auth.partssource.com/.well-known/jwks.json`            | Public keys for token validation |
| **Discovery** | `https://auth.partssource.com/.well-known/openid-configuration` | OpenID Connect configuration     |

***

## Error Responses

### 401 Unauthorized

Returned when authentication fails:

```json
{
  "type": "https://tools.ietf.org/html/rfc7235#section-3.1",
  "title": "Unauthorized",
  "status": 401,
  "detail": "Authentication is required to access this resource.",
  "correlationId": "0HN7QJKV3QJ8K:00000001"
}
```

**Common causes:**

* Missing `Authorization` header
* Invalid or malformed token
* Expired token
* Token signature validation failed

### 403 Forbidden

Returned when authentication succeeds but authorization fails:

```json
{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.3",
  "title": "Forbidden",
  "status": 403,
  "detail": "You do not have permission to access this resource.",
  "correlationId": "0HN7QJKV3QJ8K:00000001"
}
```

**Common causes:**

* Attempting cross-tenant access (CustomerApi)
* User doesn't have facility access

***

## Next Steps

* [**Obtaining Tokens**](/api/authentication/oauth-2.0-flow.md) - Detailed token request guide
* [**Token Management**](/api/authentication/oauth-2.0-flow/best-practices-and-error-handling.md) - Best practices and error handling
* [**Request API Access**](/api/authentication/requesting-oauth-2.0-client.md) - How to get your credentials


---

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