Documentation for Windows
PHP Extensions
#Installing additional PHP extensions
You may add additional PHP extensions that are not included out of the box with Herd, by downloading their dlls files from php.net and loading them via your php.ini
file.
#Adding extensions
You can browse the official pecl site and download Windows versions of the PHP extensions there.
#Activating extensions
You may activate your custom extensions by editing your php.ini
file.
This file is located at %USERPROFILE%\.config\herd\bin\<version>\php.ini
.