Let's Encrypt

Free, Automated SSL/TLS Certificates for Everyone

Let's Encrypt is a nonprofit Certificate Authority (CA) operated by the Internet Security Research Group (ISRG) that provides free, automated, and open SSL/TLS certificates to enable HTTPS encryption for websites worldwide. Since its launch in 2016, Let's Encrypt has revolutionized web security by removing the cost and complexity barriers that previously prevented millions of websites from implementing HTTPS encryption.

As of 2025, Let's Encrypt secures over 700 million websites globally, making it the world's largest Certificate Authority by volume. The service issues Domain Validation (DV) certificates that are trusted by all major browsers and operating systems, providing the same level of encryption as paid alternatives but with zero cost and fully automated issuance and renewal processes.

100% Free Forever

Let's Encrypt operates on a completely free model with no hidden costs, premium tiers, or upsells. Every feature is available to everyone:

• Unlimited certificates: Issue as many SSL/TLS certificates as you need for all your domains and subdomains
• No expiration fees: Certificates renew automatically every 90 days at no cost
• Wildcard certificates: Secure unlimited subdomains with a single wildcard certificate (*.yourdomain.com)
• Multi-domain certificates: Secure up to 100 domains with a single certificate using Subject Alternative Names (SANs)
• No validation fees: Domain validation is completely automated and free

The service is sustained through donations and sponsorships from companies and individuals who believe in a more secure Internet. Major sponsors include Google Chrome, Amazon Web Services, Mozilla, Cisco, and hundreds of other organizations.

Fully Automated Certificate Management

Let's Encrypt uses the ACME protocol (Automated Certificate Management Environment) to automate certificate issuance, installation, and renewal:

• Automated issuance: Certificates are issued within seconds after domain validation
• Automatic renewal: ACME clients automatically renew certificates before expiration
• Zero downtime: Renewals happen in the background without service interruption
• Domain validation: HTTP-01, DNS-01, and TLS-ALPN-01 challenges verify domain ownership automatically
• CLI tools: Certbot, acme.sh, and dozens of other ACME clients integrate with your hosting environment

Most modern web hosting platforms and CDN providers include built-in Let's Encrypt integration with one-click certificate installation and automatic renewal management. This includes cPanel/WHM, Plesk, AWS Certificate Manager, Cloudflare, Netlify, Vercel, and hundreds of others.

Enterprise-Grade Security Features

Let's Encrypt certificates provide the same 256-bit encryption and security standards as paid certificates:

• RSA and ECDSA support: Modern elliptic curve cryptography for faster performance
• TLS 1.2 and 1.3: Latest Transport Layer Security protocols
• 99.99% browser trust: Certificates are trusted by all major browsers (Chrome, Firefox, Safari, Edge, Opera)
• Cross-signed roots: Multiple trust chains ensure maximum compatibility
• OCSP stapling: Faster certificate validation and enhanced privacy
• Certificate Transparency: All certificates logged in public CT logs for transparency

The certificates use industry-standard validation and are indistinguishable from paid DV certificates in terms of encryption strength and browser trust indicators (the padlock icon).

ACME Client Ecosystem

Let's Encrypt supports a rich ecosystem of ACME client software for every platform and environment:

• Certbot: Official client recommended for most users, with automatic installation and renewal
• acme.sh: Lightweight shell script requiring only Unix shell, perfect for minimal environments
• Caddy Server: Web server with automatic HTTPS enabled by default using Let's Encrypt
• Traefik: Modern reverse proxy with built-in automatic certificate management
• Windows IIS clients: win-acme, Certify The Web for Windows Server environments
• DNS integrations: Native support for Cloudflare, Route 53, Google Cloud DNS, and 50+ DNS providers
• Docker containers: Official Docker images and Kubernetes integrations
• Programming language libraries: Python, Node.js, PHP, Go, Ruby, and more

The flexibility of the ACME protocol means developers can integrate Let's Encrypt into custom applications, CI/CD pipelines, and infrastructure automation workflows.

Wildcard and Multi-Domain Support

Let's Encrypt provides advanced certificate types at no additional cost:

• Wildcard certificates: Secure unlimited subdomains with *.yourdomain.com (requires DNS-01 validation)
• Subject Alternative Names (SANs): Include up to 100 domains in a single certificate
• Mix and match: Combine wildcards with specific subdomains in one certificate
• Multiple certificate types: Issue separate certificates for different purposes (www vs. API subdomains)

This flexibility makes Let's Encrypt ideal for SaaS applications, multi-tenant platforms, and complex hosting environments where you need to secure many domains efficiently.

90-Day Certificate Lifecycle (Moving to 45 Days)

Let's Encrypt certificates are valid for 90 days by design, with plans to reduce this to 45 days in 2026 to improve security:

• Security benefits: Shorter lifespans limit the window for compromised certificates to cause damage
• Forced automation: Short lifespans encourage proper automation rather than manual renewal
• Automatic renewal: ACME clients handle renewals automatically at 60-day mark (or 30 days for 45-day certificates)
• Revocation advantage: Compromised certificates expire quickly even without manual revocation
• Zero user impact: With proper automation, users never notice certificate renewals

The short certificate lifespan is actually an advantage when properly automated - it ensures your certificate management system is always working correctly and eliminates the risk of forgotten renewals that plague annual certificates.

Built-in CDN and Hosting Integration

Let's Encrypt is integrated into virtually every modern web hosting and CDN platform:

• Control panels: cPanel, Plesk, DirectAdmin include one-click Let's Encrypt installation
• Cloud providers: AWS Certificate Manager, Google Cloud Load Balancer, Azure App Service
• CDN networks: Cloudflare, Fastly, KeyCDN, BunnyCDN provide automatic Let's Encrypt certificates
• Static hosting: GitHub Pages, Netlify, Vercel, Cloudflare Pages enable HTTPS by default
• Platform-as-a-Service: Heroku, Railway, Render, Fly.io include automatic certificate provisioning
• Kubernetes: cert-manager automatically provisions and renews certificates for Kubernetes clusters

For most users, this means you don't need to interact with Let's Encrypt directly - your hosting provider handles everything automatically through their integration.

Community Support and Documentation

Let's Encrypt maintains extensive community resources and documentation:

• Community forum: Active user community providing peer support
• Comprehensive documentation: Detailed guides for every ACME client and use case
• API documentation: Complete ACME protocol specification and implementation guides
• Integration tutorials: Step-by-step guides for popular platforms and servers
• Troubleshooting guides: Common issues and solutions documented
• Rate limit information: Transparent rate limits to prevent abuse (50 certificates per domain per week)

While there's no direct email or phone support (as it's a free service), the documentation and community support are excellent, and most hosting providers offer support for their Let's Encrypt integrations.

Open Source and Transparent Operations

Let's Encrypt operates with complete transparency as an open source project:

• Open source software: Boulder CA software is fully open source (Mozilla Public License 2.0)
• Public audit logs: All certificate issuance logged in Certificate Transparency logs
• Published security practices: Security policies and incident response procedures are public
• Annual reports: ISRG publishes detailed annual reports on operations and finances
• Community governance: Technical Advisory Board includes representatives from major organizations
• No hidden agenda: Nonprofit status ensures mission alignment with user interests

This transparency builds trust and ensures Let's Encrypt remains accountable to the Internet community it serves.

Rate Limits and Fair Use

To prevent abuse while serving legitimate users, Let's Encrypt implements reasonable rate limits:

• Certificates per domain: 50 certificates per registered domain per week
• Duplicate certificates: 5 duplicate certificates per week (same exact set of domains)
• Failed validations: 5 failures per account per hostname per hour
• Accounts per IP: 10 accounts per IP address per 3 hours (can be higher with IP range registration)
• New orders: 300 new orders per account per 3 hours

These limits are very generous for legitimate use and rarely affect normal website operations. High-volume users can request rate limit increases for justified use cases.

Perfect for Every Website Type

Let's Encrypt certificates are ideal for virtually every web use case:

• Personal blogs and portfolios: Free HTTPS for your online presence
• Small business websites: Professional security without the cost
• E-commerce stores: DV certificates provide full encryption for online transactions
• APIs and web services: Secure machine-to-machine communications
• Development and staging: Free certificates for test environments
• SaaS applications: Automate certificate provisioning for customer subdomains
• IoT devices: Secure device communications with automatic certificate management
• Internal services: Even internal applications can use Let's Encrypt with DNS validation

The Catch: What Let's Encrypt Doesn't Offer

Let's Encrypt focuses on automated Domain Validation certificates, which means:

• No Organization Validation (OV): Certificates don't include company name in certificate details
• No Extended Validation (EV): No green address bar with company name (though most browsers have phased this out anyway)
• No warranty: No financial warranty coverage (though DV certificate warranties are largely symbolic anyway)
• No phone support: Community support only, no direct technical support line
• No manual issuance: Automation required - not ideal if you can't automate (though most hosting does this for you)

For most websites, these limitations don't matter - Domain Validation provides the same encryption and browser trust as OV/EV certificates, and modern browsers have de-emphasized visual differences between certificate types.

Environmental and Social Impact

Let's Encrypt has had a profound impact on Internet security:

• 700M+ websites secured: Enabled HTTPS for millions of sites that couldn't afford paid certificates
• 90%+ HTTPS adoption: Contributed to the web's transition from 40% HTTPS in 2016 to over 90% in 2025
• Privacy protection: Prevented ISP snooping and man-in-the-middle attacks for billions of users
• Developing world access: Enabled HTTPS for millions of websites in countries where paid certificates were prohibitively expensive
• Search engine benefits: Google and other search engines reward HTTPS sites with better rankings
• Browser requirements: Modern browser features (geolocation, notifications, service workers) require HTTPS, enabled by Let's Encrypt

Who Should Use Let's Encrypt?

Perfect for:

• Personal websites, blogs, and portfolios needing free HTTPS
• Small businesses wanting professional security without ongoing costs
• Developers building applications with automated certificate management
• Agencies managing multiple client websites efficiently
• Anyone with hosting that includes built-in Let's Encrypt integration
• API services and microservices requiring automated certificate provisioning
• Development and staging environments needing temporary certificates

Consider alternatives if:

• You specifically need Organization Validation (OV) or Extended Validation (EV) certificates for compliance requirements
• Your hosting environment doesn't support automation and requires manual certificate management
• You need code signing certificates, S/MIME email certificates, or other non-web certificate types
• You require guaranteed SLA and phone support (though most hosting providers offer this for their Let's Encrypt integration)

The Bottom Line

Let's Encrypt has democratized web security by making SSL/TLS certificates free and automated for everyone. For the vast majority of websites, Let's Encrypt provides exactly the same level of encryption and browser trust as paid alternatives, with the added benefits of automation and zero cost.

The 90-day certificate lifespan (moving to 45 days) is actually an advantage when properly automated, as it ensures your certificate management is always working correctly. With built-in integration in virtually every modern hosting platform and CDN, most users never need to interact with Let's Encrypt directly - it just works automatically.

Whether you're running a personal blog, a business website, an e-commerce store, or a complex SaaS application, Let's Encrypt provides enterprise-grade security at zero cost. It's the default choice for modern web development and has enabled the web's transition to HTTPS-everywhere.