Rewst

Many MSPs use Rewst to automate workflows across PSA tools, billing systems, and third-party platforms. To enable automated invoice payments and customer operations via Alternative Payments, you’ll need to authenticate and interact with our API directly through Rewst using HTTP Request blocks.

This guide walks you through how to authenticate with the Alternative Payments API inside Rewst, so you can securely trigger additional API calls from your workflows.

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📔How It Works

Rewst supports HTTP requests through its workflow automation engine, allowing you to interact directly with external APIs like Alternative Payments.

To integrate with our API:

• Authenticate using OAuth 2.0: This authentication method is used to obtain secure, server-to-server access without user interaction.

• Obtain an access token: Upon successful authentication, the API returns an access_token that is valid for a limited time.

• Authorize future requests: Use this token in the Authorization header (Bearer format) to securely access other endpoints.

• Follow standard REST practices: All API interactions are based on REST conventions, using JSON payloads, HTTP methods, and header-based authentication.

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✨Step-by-Step### 🔐 Step 1: Authenticate using HTTP Request Block

1. In your Rewst workflow, click + to add a new HTTP Request block.

2. Set Request method to POST.

3. Set URL to:

Environment	URL
Demo	https://public-api.demo.alternativepayments.io/oauth/token
Production	https://public-api.alternativepayments.io/oauth/token

In the Body section, use:

grant_type=client_credentials

Set the following Headers:

Header	Value
Content-Type	application/x-www-form-urlencoded
Authorization	Basic your_base64_credentials

🔑 Base64 Credentials

To generate the base64 credentials:

• Format your credentials as clientId:clientSecret

  You can find your clientId and clientSecret in the Partner Dashboard under the API Keys section.

• Go to https://www.base64encode.org.

• Paste the string and click Encode.\

Example

Copy the result:

and paste it in the Authorization header as:

Basic base64_encoded_value

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🧪 Step 3: Test the Request

1. Click Test in the HTTP Request block.

2. Then click View Result.

✅ If successful, you will receive a JSON response containing:

{
  "access_token": "xxxxx",
  "token_type": "Bearer",
  ...
}

Copy the access_token.

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🔁 Step 4: Use the Token in Future Requests

For any additional API calls (e.g., Listing customers, fetching invoices), include Authorization as a header:

Authorization: Bearer access_token

📌 Example endpoint:

Request

GET https://public-api.demo.alternativepayments.io/customers

Response

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🗺️Flow