Interesting how the world has changed since the 2000s here - nowadays the ecosystem is far better, so it's much easier to set up tools to mess around with this,

Interesting how the world has changed since the 2000s here - nowadays the ecosystem is far better, so it's much easier to set up tools to mess around with this, but the use of HTTPS everywhere makes it more difficult in more advanced cases (e.g. you'll often need to fight certificate configuration in individual clients). In part because of that, browser extensions have become the main way to go for this kind of local web modification, but now there's new restrictions slowly coming in there too. If you want to mess around with HTTP-level rewriting for yourself though, I maintain a Node.js library for easily writing tiny custom HTTP & HTTPS-intercepting proxies that makes it very easy: https://github.com/httptoolkit/mockttp/ https://github.com/httptoolkit/mockttp/. Others have built more specific tooling on top too, like this web page modification proxy: https://github.com/OnkelTem/wmod-proxy https://github.com/OnkelTem/wmod-proxy There's a walkthrough for setting up a quick local proxy & rewriting your own browser traffic here: https://httptoolkit.com/blog/javascript-mitm-proxy-mockttp/ https://httptoolkit.com/blog/javascript-mitm-proxy-mockttp/