­Our web services often need to integrate with third-party services that need to call back to our services. Some common instances include: success/failure notifications for actions like payment activities, hooks to listen for certain events, asynchronous processing, etc.

Third party partners usually need to set up these callbacks via their websites with a specific URL or even whitelist of IP addresses. In the absence of documentation, it can be difficult to determine the specifics of these callbacks, therefore it is necessary to guess the format of the messages.

Testing such integrations on a local machine is often difficult, hence we mainly have to use a staging environment to debug and test, which is very inconvenient to iterate and requires a new deployment for any minor change.