Payment and donation mechanisms should be easily discoverable. The solution is links - rel-payment links. Adding them to web pages or feed items that can be paid for or donated to makes it possible for browsers, apps and others to push for it in relation to your content.
Rel-Payment is a link relation standardized in the "Web Linking" standard RFC5988. As a standard link relation you can use it anywhere – in HTML pages, HTTP headers, feeds and feed items etc.
<link rel="payment" href="https://example.com/payment" type="text/html" title="Foo this through Example.com" />
href-attribute so that one can always fall back to looking it up with a simple browser. If you want to be able to use the payment link with your API then it's recommended that the API extracts the data it needs from the HTML-link rather than adding a link to an API-specific non-HTML resource.
type="text/html"attribute to the link.
titleattribute describing the purpose or target of the link - especially so if there are multiple links available in the same document as the title can then be used by clients to distinguish the different payment links from each other.
relattribute is a space delimited list of many independent relations and that it is enough for one of them to be "payment" for the link to be considered a rel-payment link.