---
title: "Authentication"
description: "How to authenticate with the Fenerum API"
url: https://www.fenerum.com/en-DK/docs/api/guides/authentication/
updated_at: "2025-12-22T00:00:00"
---
## Quick Start

Every API request requires an `Authorization` header with your token and an `X-Client-System` header identifying your application:

```bash
<!-- filename: Shell -->
curl https://app.fenerum.com/api/v1/accounts/ \
  -H "Authorization: Token your-token-here" \
  -H "X-Client-System: YourAppName"
```

> **Keep your API token secret!** Treat it like a password—never commit it to version control or expose it in client-side code.

## How Authentication Works

The Fenerum API uses token-based authentication. Include your API token in the `Authorization` header of every request using this format:

```http
Authorization: Token <your-token>
```

All requests must be made over HTTPS to `https://app.fenerum.com/`

## Getting Your API Token

Create an API token from your Fenerum organization settings:

1. Navigate to **Settings** → **Integrations**
1. Click **Create API user** in the Fenerum section

This creates an API USER with a unique token. The API USER appears in your user list and has full permissions by default—you can customize these in the user profile.

## Required Headers

Every API request must include these headers:

| Header                                                                                      | Required                                                                                    | Example                                                                                     | Description                                                                                 |
| ------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- |
| `Authorization`                                                                             | **Required**                                                                                | `Token abc123def456`                                                                        | Your API authentication token. Format: `Token <your-token>`                                 |
| `X-Client-System`                                                                           | **Required**                                                                                | `MyAwesomeCRM`                                                                              | Name of your application or integration. Used for support and audit logs.                   |
| `X-User`                                                                                    | Recommended                                                                                 | `john.doe`                                                                                  | Username in your system. Creates detailed audit trails showing which user made each change. |

The `X-User` header is particularly valuable for debugging and compliance—it lets you trace every API action back to a specific user in your system.

## Examples

### Fetching Data

```bash
<!-- filename: Shell -->
curl https://app.fenerum.com/api/v1/accounts/ \
  -H "Authorization: Token abc123def456" \
  -H "X-Client-System: MyAwesomeCRM" \
  -H "X-User: john.doe"
```

### Creating Resources

```bash
<!-- filename: Shell -->
curl -X POST https://app.fenerum.com/api/v1/accounts/ \
  -H "Authorization: Token abc123def456" \
  -H "X-Client-System: MyAwesomeCRM" \
  -H "X-User: john.doe" \
  -H "Content-Type: application/json" \
  -d '{
    "code": "CUST001",
    "name": "Acme Corporation",
    "email": "contact@acme.com"
  }'
```

### Complete HTTP Request

```http
<!-- filename: Request POST /api/v1/accounts/ -->
POST /api/v1/accounts/ HTTP/1.1
Host: app.fenerum.com
Authorization: Token abc123def456
X-Client-System: MyAwesomeCRM
X-User: john.doe
Content-Type: application/json

{
  "code": "CUST001",
  "name": "Acme Corporation",
  "email": "contact@acme.com"
}
```

## Important Details

### Base URL

All API endpoints are relative to:

```
https://app.fenerum.com/
```

### Trailing Slashes Required

**All API URLs must end with a trailing slash (`/`).**

This is critical for POST, PUT, and PATCH requests. While GET requests will auto-redirect, requests with payloads will fail without the trailing slash.

**Correct:**

```
/api/v1/accounts/
/api/v1/accounts/123/
```

**Incorrect:**

```
/api/v1/accounts
/api/v1/accounts/123
```

## Testing Your Setup

Verify your authentication with a simple request:

```bash
<!-- filename: Shell -->
curl https://app.fenerum.com/api/v1/accounts/ \
  -H "Authorization: Token your-token-here" \
  -H "X-Client-System: TestClient"
```

### Success Response (HTTP 200)

```json
<!-- filename: Response -->
{
  "count": 10,
  "next": "https://app.fenerum.com/api/v1/accounts/?page=2",
  "previous": null,
  "results": [
    {
      "uuid": "123e4567-e89b-12d3-a456-426614174000",
      "code": "CUST001",
      "name": "Acme Corporation",
      "email": "contact@acme.com"
    }
  ]
}
```

### Error Response (HTTP 401)

```json
<!-- filename: Response -->
{
  "detail": "Invalid token."
}
```

## Troubleshooting

If you receive authentication errors, check:

- **Missing `Authorization` header** — Every request must include this header
- **Wrong token format** — Must be `Token <your-token>`, not just the token value
- **Expired or revoked token** — Tokens can be disabled in user settings
- **Wrong organization** — Tokens are organization-specific and won't work across organizations
- **Missing `X-Client-System`** — This required header must be present on all requests

Still having issues? Contact our support team with your request details (excluding your token).

---

## Navigation

Up: [Subscription management & financial insights on autopilot](https://www.fenerum.com/en-DK/index.md) › [Documentation](https://www.fenerum.com/en-DK/docs.md) › [API Documentation](https://www.fenerum.com/en-DK/docs/api.md)

Full site index: https://www.fenerum.com/llms.txt