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

# Step 3: Make Your First API Call

Make your first authenticated request against Meld's Bank Linking API to confirm that your API key and provider credentials are wired up correctly.

## Before you begin

* You have completed [Step 3: Grab your Meld API key](/docs/bank-linking/onboarding/step-3-meld-api-key) and copied your API key.
* You know which environment your API key belongs to (sandbox or production).

## Steps

1. Grab your Meld API key from the **Developer** tab of the Meld Dashboard.

2. Use your API key to make a call to one of the [Bank Linking API endpoints](/api-reference/bank-linking). Prefix the key with the word **BASIC** in the `Authorization` header — for example, `Authorization: BASIC <your-api-key>`.

   ![Header with BASIC prefix](https://files.readme.io/de536d3-image.png)

3. Use the correct Base URL for the environment your key belongs to:

   | Environment | API Base URL             |
   | :---------- | :----------------------- |
   | Sandbox     | `https://api-sb.meld.io` |
   | Production  | `https://api.meld.io`    |

   You can figure out which environment your key works for by looking at the toggle in the bottom left of the Dashboard.

   ![Dashboard environment toggle](https://files.readme.io/bc53ef5-image.png)

4. Fill out all fields marked as **Required** in the API Reference; the call will fail without them.

<Warning>
  A sandbox key only works against `https://api-sb.meld.io`, and a production key only works against `https://api.meld.io`. Mixing them produces an authentication error.
</Warning>