I still use Fiddler. I prefer it to browser inspector network tab when I need to get into the weeds. It does so much, and I can write custom proxy tweaks with J

I still use Fiddler. I prefer it to browser inspector network tab when I need to get into the weeds. It does so much, and I can write custom proxy tweaks with Javascript (actually JScript.NET, but works just like good old JS), and it works with other software, I use it with NodeJS all the time. It's like the Swiss army knife of HTTP.