When developing a Webhook for a GitHub application, you may want to make calls to the GitHub API. In order to do this you will need to have a Bearer token to authorize the calls. In a typical scenario, you would obtain a token as part of the user authorization flow, but when developing a webhook for a GitHub application things work a bit differently as there is no interactive user involved.
Dropbox provides a mechanism for your application to be notified when a user’s files changes through a concept of webhooks. This means that you do not have to poll a user’s Dropbox account at certain intervals to check for changes. You simply specify the webhook and when you get notified of changes to a user’s files you can call the /delta API method in Dropbox to get the list of actual changes.