GET /dialog/donate/pay_later

Returns an HTML-based dialog that allows user to make a single donation that they can pay at a later date, using LaterPay’s micropayments via digital invoices.

Example URLs:

Available via HTTPS.

Required Parameters

campaign_id (required)

A unique identifier for tracking your donation goals (e.g., “2018-christmas-giving”, or “general-fund”). This will be used to show you analytics on how well each of your campaigns is doing. It can be any string consisting of lowercase or uppercase ASCII characters, digits, underscores, and hyphens, the length of which is between 1 and 128 characters.

title (required)

A user-friendly title that explains what the user is donating to. This will be displayed in the LaterPay dialogs and in the user’s invoice.

url (required)

The URL where the user is sent after they successfully donate. This might be your homepage, an article on your blog, or a specific landing page set up for your donation campaign. Users will see this URL in their invoices. You can also specify a return_url (see below).

cp, hmac (required)

Pricing Options

Please choose ONE of the following parameters:

custom_pricing (recommended)

A string containing currency code and price matching your currency (i.e., USD), plus the amount multiplied by 100. For example: "USD220" translates to $2.20 USD, "USD340" translates to $3.40 USD.

This parameter allows you (or your users) to change the donation amount after the link has already been generated (e.g., manually changing the URL to have custom_pricing=USD900, subject to LaterPay minimum and maximum limits).

NOTE: Do not include this parameter when signing the URL.


A string containing currency code and price, in the same format as custom_pricing above.

Use this parameter only if you want to make sure that the donation amount can’t be changed after the URL is generated. You must include this parameter as part of signing the URL.


The custom_pricing and pricing parameters are mutually exclusive. Please do not include both in the same URL.

A complete example URL for USD with custom_pricing:

Time Validation Options

Please include ONE of the following parameters:

permalink (recommended)

If this parameter is present and its value is a 1, the generated link will not expire.

We recommend this for most general user donations, and especially for use in emails.


Common Parameters

This is the timestamp of when the donation link was generated. If present, the link will expire after a certain amount of time and your users will no longer be able to use the link.

Use this if you have a specific giving campaign where you want to ensure that users can’t reuse the links to make donations again later.


The permalink and ts parameters are mutually exclusive. If permalink is 1, do not include the ts parameter.

Optional Parameters


If you would like the user to be redirected to a different URL than what appears on their invoice, you can optionally provide return_url.


If this parameter is present and its value is a 1, the user will be asked to log in before they can commit to pay later for the donation. Otherwise, users can accept the donation without having to initially sign up for a LaterPay account.