letsencrypt.org

One-line Overview

Let's Encrypt is the world’s largest free certificate authority (CA), launched by the nonprofit Internet Security Research Group (ISRG). It focuses on providing free SSL/TLS certificates for websites through automated workflows, making it the go-to choice for personal site owners, developers, and small to mid-sized businesses looking to enable HTTPS encryption.

Business Overview

Since its launch in 2015, Let's Encrypt has fundamentally changed how SSL certificates are obtained. Traditionally, websites had to pay commercial CAs such as Symantec or Comodo hundreds to thousands of dollars per year, while also dealing with a cumbersome application process. Let's Encrypt is completely free and uses the ACME protocol to automate certificate issuance, validation, and renewal. Certificates are valid for 90 days and need to be renewed automatically on a regular basis.

Its service now covers more than 300 million websites worldwide, with a commanding share of the free certificate market. Its certificates are trusted by major browsers and operating systems, including Google and Mozilla. Its user base is extremely broad, ranging from personal blogs and small e-commerce sites to large CDN providers such as Cloudflare. It is especially well suited to scenarios that require bulk deployment or fast HTTPS enablement.

Who It’s For

Let's Encrypt is best suited to four types of users. First, personal website owners and tech enthusiasts who want to enable HTTPS for small sites at zero cost. Second, small and mid-sized teams or startups that have limited budgets but need encryption for multiple domains. Third, developers, especially operations and DevOps engineers who need to manage large numbers of certificates automatically. Fourth, projects with dynamic IPs or frequently changing domains, where automated renewal helps avoid manual maintenance.

It is less suitable for scenarios that require very long certificate validity periods, such as more than one year; enterprise projects with strict brand-trust requirements, such as banks or financial institutions; or legacy server environments that cannot run an ACME client.

Key Features and Highlights

• Completely free: No fees of any kind, with no hidden costs for issuance or renewal.
• Fully automated: Uses the ACME protocol to automate the entire process of certificate application, validation, deployment, and renewal.
• Widely trusted: Certificates are natively trusted by all major operating systems, browsers, and mobile devices.
• Multiple validation methods: Supports HTTP-01 file validation, DNS-01 TXT record validation, TLS-ALPN-01, and more.
• 90-day validity: The short validity period encourages automated renewal and reduces the risk caused by leaked certificates.
• Open-source and community-driven: All code is open source, with an active community and extensive documentation.

Pricing Analysis

Let's Encrypt sits at the absolute lowest end of the pricing spectrum: it is completely free. There are no annual fees, monthly fees, domain-based charges, or hidden renewal costs. While there are rate limits, such as 50 certificates per registered domain per week, there is no practical hard cap for most users. Among similar products, zero cost is its biggest advantage.

That said, it does not offer paid value-added services commonly found with commercial CAs, such as OV/EV certificates, premium support, or warranty coverage. If you need those features, you will need to use a paid provider. Overall, for basic encryption needs, its cost-performance ratio is unmatched.

How Chinese Users Can Use It

Network accessibility: Let's Encrypt’s servers are located in the United States, but users in China can generally access its official website and ACME endpoints directly. In some domestic network environments, DNS validation may experience delays, but HTTP validation is usually smooth. No VPN or proxy is required, though using domestic mirrors or CDN acceleration, such as Let's Encrypt proxies offered by Alibaba Cloud or Tencent Cloud, can improve stability.

Payment methods: Since the service is completely free, there is no payment process.

Invoices: Because it is a free service, Let's Encrypt does not provide invoices. If you need invoices for corporate reimbursement or compliance auditing, consider using paid domestic CA services such as Alibaba Cloud SSL Certificates or Tencent Cloud SSL Certificates, which can issue VAT invoices.

Domestic alternatives: Alibaba Cloud free SSL certificates, which are valid for 1 year and require manual renewal, and Tencent Cloud free SSL certificates, which are similar. However, Let's Encrypt’s advantage is automation. Domestic alternatives usually do not support ACME-based automatic renewal and require manual operation.

Pros and Cons

Pros

• Completely free, enabling HTTPS at zero cost
• Automated deployment reduces operations workload
• Highly trusted worldwide with excellent compatibility
• Open, transparent, and backed by strong community support
• Supports wildcard certificates

Cons

• Certificates are valid for only 90 days, so automated renewal is essential; manual management can easily lead to expiration
• Does not provide OV/EV certificates, so it cannot meet enterprise-grade brand validation requirements
• DNS validation for Chinese users may occasionally be affected by network instability
• No customer support; troubleshooting depends on documentation or the community
• No warranty coverage, since it is a free service

Comparison with Similar Products

• ZeroSSL: Offers free 90-day certificates and paid 1-year certificates. It has a more user-friendly UI and supports manual management, but its free tier is limited to 3 certificates per account. Let's Encrypt is more automated and effectively unrestricted for typical use.
• BuyPass Go: Another free CA with certificates valid for 180 days, but its trust coverage is slightly below Let's Encrypt and its community is smaller.
• Alibaba Cloud/Tencent Cloud free SSL: Free versions from domestic commercial CAs, valid for 1 year, but they require manual renewal and do not support ACME automated deployment. They suit users who do not want to set up automation. Let's Encrypt is far ahead in automation.

Final Recommendation

Let's Encrypt is best for scenarios that require automation, zero cost, and fast deployment, such as personal blogs, small websites, development and testing environments, and CDN origin servers. If you can accept the 90-day automatic renewal model and do not need OV/EV certificates, it is almost the optimal choice.

It is not suitable for cases with strict requirements around certificate validity periods, such as more than 1 year; situations requiring human customer support or invoices; or legacy systems that do not support the ACME protocol. For all new projects, we recommend trying Let's Encrypt first. It is free to use and requires no upfront investment.