(This is a quick review of a chrome extension). While your website or section of it is being built, private, not-finished, admin pages without logins or due to some reasons, you want to protect temporarily, there is a quick solution.
extension
XDebug: Optimal Personal Configurations
I initiate XDebug on demand, via URL parameters. But XDebug configurations in php.ini has to be configured accordingly to accept those requests and obey them. Thus, only the scripts that need debugging or tracing or profiling will request the particular service. Keeping memory and CPU free is also important.