Simple Callback Server

It’s the simplest thing you could imagine: An express server that prints out all headers and the body or all query parameters. Still, I needed it sometimes and I didn’t want to rewrite it every time I use it.

When creating a dev application on Google, Spotify, or other services you often have some heavy authentication flow to get access. But normally I want to use the API for private projects and it’s my account that gets authenticated every time.

To make reauthentication easier these OAuth protocols often provide a "refresh token" which can be used to get a valid new token.

To get the initial authentication token and to get such a refresh token you provide a callback address where you get redirected after the user logs in. The tokens and meta information normally are sent in a POST body. And this is where this small application is necessary.