> For the complete documentation index, see [llms.txt](https://docs.payrexx.com/merchant/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payrexx.com/merchant/english/account/tools/parameters.md).
# Parameters
In this article, you will learn how to customize payment form links in Payrexx using URL parameters.
By appending parameters to the URL of a payment form, you can set default values and thereby personalize the form.
## Overview of All Parameters
The following overview shows which parameters are available in the various forms.
### Global parameters
The following parameters work across all [e-commerce tools](/merchant/english/account/tools.md) in Payrexx:
| **Name** | **Parameter** |
| ------------------------------------------------------------------ | ----------------- |
| Amount (Default) | invoice\_amount |
| Amount ([Terminal](/merchant/english/account/tools/terminal.md)) | amount |
| Currency (Default) | invoice\_currency |
| Currency ([Terminal](/merchant/english/account/tools/terminal.md)) | currency |
| Purpose (Default) | invoice\_number |
| Purpose ([Terminal](/merchant/english/account/tools/terminal.md)) | purpose |
| Salutation | contact\_title |
| First name | contact\_forename |
| Last name | contact\_surname |
| Company | contact\_company |
| Street | contact\_street |
| ZIP Code | contact\_postcode |
| Place | contact\_place |
| Country | contact\_country |
| Phone | contact\_phone |
| Email | contact\_email |
| Text field content | contact\_text |
| Multiline text field content | contact\_textbox |
| Discount code | code |
| Reference | referenceId |
### Parameters for the Donation tool
The following parameters work only in the "Donation" tool:
| **Description** | **Parameter** |
| --------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------ |
| The amount of 50 is proposed. Can be changed by the donor.
\[Values: Amount, amount with decimal point (e.g. 10.50)].
| donation\[preselect\_amount] |
| Interval is selected. Can no longer be changed.
\[Values: one\_time, weekly, monthly, quarterly, annually]
| donation\[interval] |
| Interval is proposed. Can still be changed by the donor.
\[Values: one\_time, weekly, monthly, quarterly, annually]
| donation\[preselect\_interval] |
| The purpose of the donation is pre-selected and can be changed by the donor.
\[Values: 1,2,3,...]
| donation\[preselect\_purpose] |
| The campaign description is hidden.
\[Values: 0.1]
| hide\_description |
## Examples of Using URL Parameters
The following examples illustrate how you can use URL parameters with Payrexx [e-commerce tools](/merchant/english/account/tools.md).
{% hint style="info" %}
A question mark (**?**) must precede the first URL parameter, and each additional parameter is introduced with an **&**.
{% endhint %}
| Link with URL parameters | Function |
|---|
| https://[instance].payrexx.com/en/vpos?amount=19.50 | When the terminal is opened, the amount of 19.50 is pre-defined. |
| https://[instance].payrexx.com/en/vpos?amount=19.50&purpose=Test | When the terminal is opened, the amount of 19.50 and the payment purpose “Test order” are pre-defined. |
| https://[instance].payrexx.com/en/pay?tid=fbd71f97&contact_title=Mr&contact_forename=John&contact_surname=Smith | When the payment page is opened, the fields "Title", "First name", and "Last name" are automatically populated with "Mr", "John", and "Smith". |
| https://[instance].payrexx.com/en/pay?cid=74eb3a66&donation[preselect_amount]=50 | When the donation page is opened, the amount of 50.00 is automatically selected, but can still be modified by the donor. |
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