Are you using an LWP app, and trying to debug it? My personal preferences is using mitmproxy.
To get LWP to use mitmproxy, set the following ENV variables:
PERL_LWP_ENV_PROXY=1 HTTPS_PROXY='http://localhost:8080/' ./script/myapp
Note, this also works for apps using Mojo::UserAgent, except you don't need the first ENV variable.