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

# Authentication

> Authenticate to the FlexiCapture for Invoices Cloud API using HTTP Basic Auth: combine your application ID and token, and then Base64-encode them for the header.

Authentication to the API is performed via [HTTP Basic Auth](https://en.wikipedia.org/wiki/Basic_access_authentication).

All requests to the API must contain an authorization header. To get the authorization header, use the application credentials: the application identifier and token.

Applications in ABBYY FlexiCapture Cloud specify the settings that are used to process the uploaded documents. They determine the document type, the list of fields to be extracted, the rules to be checked, and more. If you have several applications, you can choose which one to use depending on your needs. You can view the application credentials and change the active application on the **Applications** page in the [ABBYY FlexiCapture Cloud web portal](https://flexicapture.com).

## Get the authorization header

<Steps>
  <Step title="Concatenate the credentials">
    Concatenate the application identifier and the token, using a colon as a separator.
  </Step>

  <Step title="Encode the string">
    Encode the resulting string using any variant of Base64.
  </Step>

  <Step title="Add the authorization method">
    Add the authorization method followed by a space in front of the encoded string.
  </Step>
</Steps>

### Example

For an application ID of `Aladdin` and a token of `OpenSesame`:

1. Concatenate the application ID and the token:

   ```text theme={null}
   Aladdin:OpenSesame
   ```
2. Encode the string using any variant of Base64:

   ```text theme={null}
   QWxhZGRpbjpPcGVuU2VzYW1l
   ```
3. Add the authorization method followed by a space in front of the encoded string:

   ```text theme={null}
   Basic QWxhZGRpbjpPcGVuU2VzYW1l
   ```

The resulting authorization header is:

```text theme={null}
Authorization: Basic QWxhZGRpbjpPcGVuU2VzYW1l
```