How to Install Let's Encrypt on IIS Windows Server

Definition of IIS


IIS is the only web server software that can be used, if you are a server owner with a Windows operating system. 


What is Let's Encrypt

Let's Encrypt is a free, automated and open certificate authority (CA), run for public benefit. We are a service provided by the Internet Security Research Group (ISRG). 509 certificates for Transport Layer Security encryption are free of charge. It was first introduced in 2016, and today Let's Encrypt is one of the most famous and widely used SSL publishers.


To conclude that Let's Encrypt is a free SSL provider that you can install on the web server currently in use.

How to Install Let's Encrypt IIS

Here are the steps on how to install Let's Encrypt IIS:


Binding Port 443 IIS

Make sure before installing Let's Encrypt SSL that you have Bind port 443 on the Site in IIS so that later the website can be accessed via https. If not yet done, you can follow these steps first,

  1. Login to IIS Manager
  2. After entering the IIS Manager, please select the Sites that will be bound, and select Bindings
  1. Next please select Add


    4. A new window will appear where you will be asked to complete the site information,

  • Type: Select https
  • Port: Fill with 443
  • Hostname: fill in the domain name
  • SSL Certificate: fill in the existing default certificate



  1. After completing, select OK to add the Binding site.
  1. If successful, a site with port 443 will appear according to the following image,

Install Let's Encrypt

To install Let's Encrypt on IIS will utilise the Win Acme or ACMEv2 application.


  1. Access the Win Acme website.
  2. After that download the application,
  1. Next, a file will be downloaded in .zip format. When finished, please extract the file and run the wacs.exe file as shown below,
  1. After that the ACMEv2 Client application will appear, and several options will appear. To Install SSL please select option N or Create Certificate (default settings),
  1. Next, in the Site Identifier, press Enter to scan all domains in IIS.
  1. Next there will be several dialogues where you have to choose,
  • Binding Identifiers(s) or menu options : A
  • Continue With this selection? : ketik yes
  • open in default application? : ketik yes
  • Do you aggree with the terms? : ketik yes
  • Enter Email (s): fill in the email address to receive notifications
  1. After completing all then the SSL Installation process will begin. Please wait a few minutes for the installation process.
  1. If the SSL Installation process is complete, information will appear as shown below,
  1. After the Let's Encrypt SSL Installation process is complete. Please try to access the website.

That's how to install Let's Encrypt on IIS Windows Server. Good luck.

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