Switchyroo

Simply needed an image replaced with another. Tampermonkey script would have you wait for page to load before you can replace the object. This extension can replace it before the page loads. Perfect! Thank you for this extension, developer. Update: One snag, every now and again it stops replacing the resource and the page needs an emptying of cache and a hard reload.

Works, but 1) It doesn't modify the URL in the browser after the redirect, so eg the browser still shows www.reddit.com but the CONTENTS are showing old.reddit.com and 2) it doesn't "show which redirect URLs were executed after opening" ie I have no idea that it redirected apart from seeing the content of the redirected URL in the browser viewport.

Thank you for building this! I love its simplicity

This tools is exactly what I was looking for, simplicity and it works as expected. Great work!