> ## Documentation Index
> Fetch the complete documentation index at: https://nango.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# BigChange - How do I link my account?

# Overview

To authenticate with BigChange, you will need:

1. **Partner API Client ID and Client Secret** — issued by BigChange to the integrator (set once per Nango integration).
2. **Customer ID** — the numeric Customer ID for the BigChange tenant you are connecting (per Nango connection).

BigChange uses OAuth 2.0 Client Credentials authentication: a single Partner API `client_id` and `client_secret` are configured at the Nango integration level, and each individual BigChange customer is identified by their numeric Customer ID, passed in the `customer-id` request header.

### Prerequisites:

* Access to the [BigChange Developer Portal](https://developers.bigchange.com) with permission to create Partner API keys.
* The numeric Customer ID for each BigChange tenant you intend to connect.

### Instructions:

#### Step 1: Generate your BigChange Partner API credentials

1. Sign in to the [BigChange Developer Portal](https://developers.bigchange.com).
2. Navigate to **API Key Management**.
3. Click **Create new API Key**, give it a descriptive name, and confirm. BigChange will issue a `client_id` and `client_secret`.
4. Copy both values. The `client_secret` is shown only once.
5. In your Nango BigChange integration settings, paste the `client_id` and `client_secret` into the **Client ID** and **Client Secret** fields. These are shared across every BigChange tenant you connect.

#### Step 2: Find your BigChange Customer ID

1. Sign in to the [BigChange Developer Portal](https://developers.bigchange.com).
2. Navigate to **API Key Management**. The numeric Customer ID is shown in the page description, e.g. `5690`.

<Tip>The Customer ID is numeric only — digits 0-9.</Tip>

#### Step 3: Enter credentials in the Connect UI

Once you have your **BigChange Customer ID**:

1. Open the form where you need to authenticate with BigChange.
2. Enter your **BigChange Customer ID** in its respective field.
3. Submit the form, and you should be successfully authenticated.

You are now connected to BigChange.