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

# Step 1: Create an API key for use with Secure Fields

Before your application can communicate with the API you will need to
create a new API key. The API handles authentication using a signed **JSON
Web Token** (JWT) which is passed in a HTTP header.

```bash theme={"dark"}
curl -X GET https://api.mattildapayments.com/transactions \
  -H "authorization: bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIi..."
```

<Tip>
  We recommend you use an SDK. Our SDKs makes the process of generating a token a lot easier and is probably
  available in your preferred programming language. We will get to this in the
  next step.
</Tip>

## Create a new API key

To use the API you will need to generate a new **API key**. Ask your Account Manager for an API key, which will come in a .pem file, in order to start with your integration.

<Info>
  Learn more about private keys, key-pairs, and JWT in our
  [in-depth guide on authentication](/guides/api/authentication).
</Info>

## Summary

In this step you:

* Learned about API authentication.
* Created a new private key for the API.
* Stored this API key in a secure place where your application can access it.