How to enable Strict-Transport-Security (HSTS) for domain in Plesk for Linux and Windows servers?

For Linux:

1. Login to Plesk

2. Go to Plesk > Domains > example.com > Hosting Settings > enable Permanent SEO-safe 301 redirect from HTTP to HTTPS

3. Go to Domains > example.com > Apache & nginx Settings and add the following custom value in Additional headers section:

   Strict-Transport-Security: max-age=63072000; preload

   Note: Strict-Transport-Security parameters are shown as an example only, the custom directive may vary depending on the site owner needs.

For Windows:

1. Enable Require SSL for domain and all subdomains in Plesk > Domains > example.com > IIS Settings ; 
   
2. Connect to the server via RDP ;
3. Go to IIS > ServerName > Sites > example.com > HTTP Response Headers > Add ...
4. Submit fields as follows: 
   

   Name: Strict-Transport-Security 
   Value: max-age=31536000; includeSubDomains; preload