Before getting started with tipping, you must first implement authentication in your application.
Since the same person may have different usernames on each site they use, your site will need to provide ChangeTip with the user ID and/or username of that person as it is stored on your site so that when tips are sent to users of your application, the identity of the recipient can be confirmed.
In other words, ChangeTip needs to know that user "bobjones" on ChangeTip might be user "bob" with userID "123" on your site.
After a user successfully logs in with ChangeTip, your app should send the ID and username by sending a POST request to the /v2/verify-channel-user/ endpoint. As long as the user's username doesn't change, this call only needs to be made one time. However, if the username (on your site) changes, this endpoint can be called again to update it on ChangeTip.
Once you've connected users and verified their identities on your site, sending tips is simple. Simply follow the directions at the /v2/tip/ endpoint.