[101008]

Proxyman looks like something I always wanted: does it allow you to say "when any browsers/webpage request this URL {url}, return this {content} instead of the original one"? And if it works like that, does anyone know something like that for Windows? Thanks!

[sachinjain]

Yes, You can do this with Requestly desktop app. You can use Modify Response feature to just specify a URL then specify the status code you need like 400 or 500 and then you can also specify what content do you want to return.

Requestly also lets you write a simple JS script to change something in the existing content. Here are some references for you - About Modify Response (https://requestly.io/feature/modify-response/), Change Status Code (https://stackoverflow.com/questions/50923170/simulate-fake-4...).

And yes, Requestly is available on Windows too.