Clearhaus
Clearhaus offers Visa and Mastercard acquiring. Their prices and terms of service can be found on their website: https://www.clearhaus.com/pricing/
Order an acquiring agreement
You can apply for a Clearhaus agreement directly through OnPay. Click Apply here under the Clearhaus settings:

This will take you to a Clearhaus application form to be filled out with your company information and contact details:

Once the application has been sent to Clearhaus, you will shortly receive confirmation from them with details of your new agreement with them. However, you can continue with the setup in OnPay immediately after the application has been sent, as OnPay is automatically assigned an API key that can be used right away.
Configuration in OnPay
Once your agreement with Clearhaus is set up, you will need the corresponding API key, which can be found in your Clearhaus control panel. To set up Clearhaus you need to go to Settings > Acquirers > Clearhaus and complete the following steps:
- Activate Clearhaus
- Check that the API key is set (automatically assigned for new agreements through OnPay)
- Click Save

When saving your changes you will be prompted with a dialog asking you to enable Clearhaus as the primary acquirer for Visa and Mastercard. Click on Set as primary:

If you are using another acquirer already as your primary acquirer and don't want to switch to Clearhaus right away, select No instead. Primary and secondary acquirers can always be set under Card rules
You will notice that your agreement is now automatically loaded from Clearhaus:

Notice: After setting up the acquirer we recommend that you complete a test payment with your own payment card to ensure that your agreement has been propagated and that OnPay has established a valid connection to the acquirer.