Certify The Web allows you to generate and then install an SSL certificate for free! In particular, it makes it possible to secure (httpS) an Exchange server or remote desktop gateways.
Certify The Web is easy to install on Windows Server. Once installed, just follow a wizard to deploy your SSL certificate for free. Certify The Web is fully compatible with IIS (Microsoft's web server functionality).
There are paid certificates that you can obtain from authorized resellers such as Global Sign, for example, Certify The Web relies on the free Let's Encrypt solution and takes care of renewing the certificate automatically.
Download Certify The Web from the official website : https://certifytheweb.com
Navigate to the Settings tab and click on the Certificate Authorities. Make sure the Preferred Certificate Authority is on Let’s Encrypt. Click on New Account
Type your email address, agree and click on Register Contact
After registering then you can click on New Certificate and type *.yourdomain.com in the domain input field where the * means secure all subdomains under the primary domain and click on the plus sign. if you prefer to add non-wildcard version you can click on Yes or No.
Now click on the Authorization section on the right side and select dns-01 in the Challenge Type drop-down. In the DNS Update Method drop-down select (Update DNS Manually) and Click on the Test button to test the domain status if everything appears ok.
To move forward you need to create a DNS (TXT) record in your DNS settings and you will receive a message like the one below in the email account that you configured earlier. Open the DNS Settings and create your TXT Record.
Once the test is successful you can go to the Deployment section and in the Deployment Mode drop-down you can select Certificate Store Only.
The reason for this selection is because this will store the SSL certificate in your local database. Note that the SSL certificate obtained through the Certify the Web application has a PFX extension that is not compatible with the Apache server by default, so we must convert that file to make it compatible with the Apache server. Same like exemple here :