Learn how to configure Let’s Encrypt SSL on Windows 11 using Win-ACME and IIS.
Securing your website with HTTPS is no longer optional—it’s a necessity. Whether you’re hosting a personal blog, business site, or development project, installing an SSL certificate ensures encrypted communication between your server and visitors.
If you're running a web server on Windows, this guide will show you how to generate SSL certificate Let’s Encrypt Windows 11, configure it properly, and automate renewals using Win-ACME and IIS.
You may check my older article, right? - if not learn, How to Create Let’s Encrypt SSL Certificate on Windows (Step-by-Step Guide)
By the end of this tutorial, you’ll have a fully functional free HTTPS Windows setup.
Why Use Let’s Encrypt on Windows 11?
Let's Encrypt is a free, automated, and open certificate authority (CA) that provides SSL/TLS certificates at no cost. It’s trusted by all major browsers and widely adopted worldwide.
Benefits include:
100% Free SSL certificates
Automated issuance and renewal
Trusted by browsers
Secure HTTPS support
Easy setup with tools like Win-ACME
For developers and small businesses running IIS on Windows 11, this is the easiest and most cost-effective solution.
Prerequisites Before You Start
Before you begin the Let’s Encrypt Windows 11 setup, make sure you have:
Windows 11 installed
IIS (Internet Information Services) enabled
A registered domain name pointing to your public IP
Port 80 (HTTP) open in firewall/router
Administrator access to your PC
Step 1: Install IIS on Windows 11
If IIS is not already installed:
Press Win + R, type
appwiz.cpl, and press Enter.Click Turn Windows features on or off
Enable:
Internet Information Services
IIS Management Console
World Wide Web Services
Click OK and wait for installation.
After installation:
Open browser
Visit
http://localhostYou should see the IIS welcome page
Now IIS is ready for SSL for IIS configuration.
Step 2: Download Win-ACME Client
To request certificates from Let’s Encrypt on Windows, you’ll use:
Win-ACME
Win-ACME (WACS) is an ACME client built specifically for Windows servers. It automates certificate issuance and renewal.
Download Steps:
Visit the official Win-ACME GitHub page
Download the latest stable release ZIP
Extract it to a folder like:
C:\win-acme
Step 3: Run Win-ACME to Generate SSL Certificate
Now comes the important part — generating the certificate.
Open Command Prompt as Administrator
Navigate to:
cd C:\win-acme
Run:
wacs.exe
You’ll see a menu like:
N: Create certificate (default settings)
M: Create certificate (full options)
Choose:
N
Win-ACME will:
Detect IIS sites automatically
List all hosted domains
Ask which site you want to secure
Select your domain from the list.
Step 4: Domain Validation (HTTP-01 Challenge)
Let’s Encrypt verifies domain ownership using HTTP validation.
Win-ACME will:
Create temporary validation files
Place them in your IIS web root
Let Let’s Encrypt verify your server
If your domain is correctly pointed and port 80 is open, validation will succeed automatically.
After verification, the certificate is issued instantly.
Step 5: Automatic SSL Installation for IIS
One of the best parts of Win-ACME Windows setup is that it automatically:
Installs certificate in Windows Certificate Store
Binds HTTPS to your IIS site
Configures port 443
Sets correct SSL binding
To confirm:
Open IIS Manager
Select your website
Click Bindings
You should see:
Type: https
Port: 443
Certificate: Your Domain
Now your site should load securely:
https://yourdomain.com
Step 6: Force HTTPS Redirection
To complete your free HTTPS Windows setup, redirect HTTP traffic to HTTPS.
Method 1: Using URL Rewrite (Recommended)
Install URL Rewrite module (if not installed)
Open IIS Manager
Select your website
Open URL Rewrite
Click Add Rule(s)
Choose Blank Rule
Configure:
Condition:
{HTTPS} offAction: Redirect
Redirect URL:
https://{HTTP_HOST}/{R:1}Redirect Type: Permanent (301)
Now all visitors will be automatically redirected to HTTPS.
Step 7: Automatic Renewal Configuration
Let’s Encrypt certificates expire every 90 days.
Luckily, Win-ACME sets up:
Windows Scheduled Task
Automatic renewal check
Silent renewal process
To verify:
Open Task Scheduler
Look for Win-ACME task
Confirm it runs daily
You don’t need to manually renew your certificate.
Troubleshooting Common Issues
1. Validation Failed
Check:
Domain DNS is correct
Port 80 is open
No firewall blocking traffic
2. HTTPS Not Working
Verify:
SSL binding exists in IIS
Port 443 open
Certificate installed correctly
3. Mixed Content Warning
If browser shows insecure warning:
Update internal links to HTTPS
Check images, scripts, CSS
Fix hardcoded HTTP URLs
Why HTTPS Is Important for SEO
Google prioritizes HTTPS websites in search rankings.
SSL provides:
Data encryption
Improved trust
Better SEO ranking
Secure login forms
Protection from MITM attacks
For deeper understanding of SSL and encryption concepts, you can explore helpful technical breakdowns on platforms like Medium’s BeingCoders section, especially discussions around SSL implementation available at https://medium.com/beingcoders/search?q=ssl. (these are the best articles to refer)
Additionally, if you're exploring broader Windows hosting optimizations, server tuning, or web security practices, resources on platforms like 9mood.com provide valuable technical insights for developers and system administrators.
Security Best Practices After Installation
Once SSL is installed:
Enable HTTP Strict Transport Security (HSTS)
Disable old TLS versions (TLS 1.0, 1.1)
Enable TLS 1.2 / 1.3 only
Keep Windows updated
Monitor certificate expiry logs
Advanced: Multiple Domains (SAN Certificate)
If your IIS hosts multiple domains:
Win-ACME allows:
SAN (Subject Alternative Name) certificates
Wildcard certificates (DNS validation required)
Manual or advanced configurations
For wildcard certificates, DNS-01 challenge is needed.
Summary: Complete Let’s Encrypt Windows 11 Setup
You’ve successfully learned how to:
✔ Install IIS
✔ Download Win-ACME
✔ Generate SSL certificate Let’s Encrypt Windows
✔ Configure SSL for IIS
✔ Enable automatic renewal
✔ Force HTTPS redirect
This method is:
Free
Secure
Automated
SEO friendly
Production ready
Final Thoughts
Setting up Let’s Encrypt Windows 11 with Win-ACME is one of the easiest ways to secure your IIS website without spending money on commercial certificates.
In today’s digital world, HTTPS is mandatory—not optional. Whether you're hosting a blog, business site, or internal application, implementing SSL ensures encrypted, trusted communication.
With this complete Win-ACME Windows setup guide, you now have everything needed to secure your Windows 11 web server professionally and efficiently.
If you’re planning to deploy more production-ready Windows servers, consider automating security practices and regularly reviewing best SSL configurations to maintain long-term reliability.
