Proxyman is a native OSX HTTP Debugging Proxy app, which is capable of proxying and intercepts the HTTP/HTTPS requests. The app helps you debug your HTTPS request from apps, domain, remove devices and iOS simulator and replicate the requests.
DebugBear is a tool to help developers monitor front-end code and performance. You'll get alerts when your JS bundle gets a lot bigger or if there's a new error in the console logs.
There's also a full archive of all requests, so you can simulate loading an application as it was deployed e.g. two weeks ago.