Let's Encrypt

Let’s Encrypt is a Certificate Authority that issues certificates for secure connections to domain-named servers. It suits people and organizations who can manage certificates on their own infrastructure. Free DV certificates and ACME automation make it a strong fit for routine HTTPS needs, while its fixed lifetimes and lack of direct subscriber support call for dependable operations.

Overview

Let’s Encrypt verifies domain control through ACME and issues Domain Validation (DV) certificates. Compatible clients can automate certificate management, deployment, and renewal, reducing recurring manual work for operators who can configure and maintain those clients. The same approach serves web, mail, and FTP servers.

Certificates are trusted by most browsers and operating systems, and issued and revoked certificates are publicly recorded for inspection. Private keys are generated and managed on subscribers’ own servers rather than stored by Let’s Encrypt. That leaves key custody with the subscriber, who must also secure and maintain those keys.

The scope is deliberately limited to domain validation: Let’s Encrypt says it has no plans to issue Organization Validation or Extended Validation certificates. Choose another certificate provider if your requirements call for either of those certificate types.

Key features

• ACME certificate automation: Clients can automate issuance, deployment, and renewal. This is useful for operators managing certificates across servers, but the result depends on a working client setup and reliable maintenance.
• Broad client coverage: The client directory includes Apache HTTP Server, Caddy, nginx, Kubernetes, Docker, and Windows/IIS environments, among others. That range gives operators several paths to fit certificate management into their infrastructure.
• Wildcard certificates: Wildcards are available, but issuance requires the DNS-01 challenge. Operators need to be able to complete that DNS-based verification.
• Two fixed validity options: Default certificates last 90 days, with an optional six-day certificate. Subscribers cannot adjust either lifetime, so renewal automation is central to avoiding expired certificates.
• Subscriber-held private keys: Keys stay on subscribers’ servers. This keeps control local, while making key security and storage the subscriber’s responsibility.
• Public certificate records: Issued and revoked certificates are recorded publicly and can be inspected. Operators should account for that visibility when deciding whether the service fits their use case.
• Published rate limits: A registered domain can receive up to 50 certificates every seven days, subject to the published rate limits. That allowance is substantial for many routine deployments, but operators managing larger certificate volumes must plan around the limits.

Pricing

Let’s Encrypt certificates cost nothing, billed Free. There is no fee for certificates, and the plan includes DV certificates with default 90-day validity or the optional six-day validity. Automatic renewal and deployment automation are supported, alongside revocation workflows. There is no free trial because the service is free.

The zero-fee plan is suited to individuals and organizations that can run compatible clients and manage their own certificate operations. It does not include OV or EV certificates, and certificate lifetimes cannot be customized. The tradeoff is operational: subscribers need to maintain automation, protect server-held keys, and use documentation or community forums for support because Let’s Encrypt does not offer direct subscriber support.

Platforms

Let’s Encrypt lists API, Linux, self-hosted, web, and Windows platforms. Its client directory names integrations for common web servers, container environments, Kubernetes, and Windows/IIS, supporting use across varied server setups.

Who it's for

Let’s Encrypt is a good choice for people and organizations worldwide that need certificates for domain-named web, mail, or FTP servers and can manage them on their own infrastructure. It fits especially well where DV is sufficient and ACME automation can handle recurring renewals.

It is a poor fit for teams that need OV or EV certificates, adjustable certificate lifetimes, or direct subscriber support. Operators who cannot reliably maintain clients and renewal workflows should consider whether the fixed validity periods create too much operational risk.

Pros and cons

• Pro — No certificate fee: The free plan provides DV certificates without a charge, making it suitable for deployments that need certificates without a certificate budget.
• Pro — Renewal and deployment automation: ACME clients can automate recurring certificate work, reducing manual renewals when the client environment is properly maintained.
• Pro — Subscriber control of private keys: Keys remain on the subscriber’s servers rather than being held by the Certificate Authority.
• Con — DV certificates only: There are no OV or EV certificates for organizations whose requirements call for those types.
• Con — Fixed lifetimes: Certificates last 90 days by default or six days by choice, with no option to set a different term. This makes working renewal processes essential.
• Con — No direct subscriber support: Help is directed to documentation and community forums, which may not suit operators who need direct assistance.
• Con — Public certificate records: Issued and revoked certificates are publicly inspectable, which may not suit every certificate-management need.

Alternatives

For a broader comparison, browse Public Key Infrastructure Software and Certificate Management Software.

• OpenCA PKI is another free, self-hosted PKI option, with Linux, macOS, and web platforms.
• step-ca is a free option for operators who want an offline root CA, a configured intermediate CA, and authority-wide issuance policies; it has no Certificate Transparency integration.
• EJBCA offers a free Community Edition for learning, testing, and prototyping, rather than production use.
• OpenXPKI has a free Community Edition with Debian packages, example configuration, documentation, and mailing-list support.
• SecureW2 Cloud NAC uses quote-based pricing for organizations seeking a paid option.
• XiPKI is a free, open-source option that supports API, Linux, macOS, and self-hosted platforms.
• EZCA is a paid alternative with a $200 / CA / month Basic plan and FIPS 140-3 Level 2 HSM-backed CAs.
• Boulder is a free, open-source option whose production deployment requires separate implementation and security work.

Verdict

Choose Let’s Encrypt if you need free, trusted DV certificates for domain-named servers and can keep ACME issuance and renewal running reliably. Its broad client coverage and subscriber-held keys make it practical for self-managed infrastructure. Look elsewhere when you need OV or EV certificates, custom validity periods, or direct subscriber support.