Let's Encrypt for Local Xampp Server use
add a free SSL certificate to your development server
You can use the SSL certificates generated by this site for XAMPP or any other Apache Server installation, easy enough.
But, you can also use Let's Encrypt SSL certificates on your development server.
Suppose you have a domain like "example.com", then you probably have subdomains like "www" listed in your DNS records for that domain. But, you can add A records, like "home.example.com", "test.example.com", "sever1.home.example.com" with the IP address of your local webserver installation.
Or even better, a wildcard DNS entry like "*.home.example.com" with you local IP, then you have zillions of possibiliies. Just install the Let's Encrypt certificates for every (sub) domain on your local server like "test.home.example.com", "site1.home.example.com" etc. As an addtional bonus every device on you local netwerk then has access too!
Like with the SSL certificates from this site, see: Share server
Generate a free wildcard Let's Encrypt SSL certificate https://punchsalad.com/ssl-certificate-generator/
There seem to be a load of "Free SSL" websites nowadays that still are after your money (or email address), sadly. But this is one is really free.
Thanks Punch Salad!
(You need access to your DNS entries!)