Let's Encrypt is a free, automated, and open Certificate Authority brought to you by the nonprofit Internet Security Research Group (ISRG). Read all about our work in our Annual Report.
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As of the end of July 2018, the Let’s Encrypt root, ISRG Root X1, is directly trusted by Microsoft products. Our root is now trusted by all major root programs, including Microsoft, Google, Apple, Mozilla, Oracle, and Blackberry. Today’s announcement that we’re trusted by all major root programs represents a major…
We’re pleased to announce that we’ve received cross-signatures from IdenTrust, which means that our certificates are now trusted by all major browsers. This is a significant milestone since it means that visitors to websites using Let’s Encrypt certificates can enjoy a secure browsing experience with no special…
We’re happy to announce that Let’s Encrypt has entered Public Beta. Invitations are no longer needed in order to get free certificates from Let’s Encrypt. It’s time for the Web to take a big step forward in terms of security and privacy. We want to see HTTPS become the default. Let’s Encrypt was built to enable that…
We issued our billionth certificate on February 27, 2020. We’re going to use this big round number as an opportunity to reflect on what has changed for us, and for the Internet, leading up to this event. In particular, we want to talk about what has happened since the last time we talked about a big round number of…
Let’s Encrypt passed another major milestone by issuing our first certificate. You can see it in action here. Our cross signature is not yet in place, however this certificate is fully functional for clients with the ISRG root in their trust store. When we are cross signed, approximately a month from now, our…
Let’s Encrypt is leaving beta today. We’re also excited to announce that founding sponsors Cisco and Akamai have renewed their Platinum sponsorships with 3-year commitments, Gemalto is joining as our newest Gold sponsor, and HP Enterprise, Fastly, Duda and ReliableSite.net are our newest Silver sponsors. Since our…
Update, March 13, 2018 Wildcard certificate support is live. Let’s Encrypt will begin issuing wildcard certificates in January of 2018. Wildcard certificates are a commonly requested feature and we understand that there are some use cases where they make HTTPS deployment easier. Our hope is that offering wildcards…
Update, July 10, 2023 See our new blog post for details on the September 2024 expiration of the newer ISRG Root X1 cross-sign from IdenTrust. Update, December 21, 2020 Thanks to community feedback and our wonderful partners at IdenTrust, we will be able to continue to offer service without interruption to people using…
Let’s Encrypt has reached a milestone: we’ve now issued more than 100,000,000 certificates. This number reflects at least a few things: First, it illustrates the strong demand for our services. We’d like to thank all of the sysadmins, web developers, and everyone else managing servers for prioritizing protecting your…
When Let’s Encrypt first launched, we needed to ensure that our certificates were widely trusted. To that end, we arranged to have our intermediate certificates cross-signed by IdenTrust’s DST Root CA X3. This meant that all certificates issued by those intermediates would be trusted, even while our own ISRG Root X1…
Update: March 11, 2026 If you use Certbot, see Six-Day and IP Address Certificates Available in Certbot for details on requesting these certificates. Short-lived and IP address certificates are now generally available from Let’s Encrypt. These certificates are valid for 160 hours, just over six days. In order to get a…
On Thursday, September 3rd, 2020, Let’s Encrypt issued six new certificates: one root, four intermediates, and one cross-sign. These new certificates are part of our larger plan to improve privacy on the web, by making ECDSA end-entity certificates widely available, and by making certificates smaller. Given that we…
Our first full year as a live CA was an exciting one. I’m incredibly proud of what our team and community accomplished during 2016. I’d like to share some thoughts about how we’ve changed, what we’ve accomplished, and what we’ve learned. At the start of 2016, Let’s Encrypt certificates had been available to the public…
Today we are announcing our intent to end Online Certificate Status Protocol (OCSP) support in favor of Certificate Revocation Lists (CRLs) as soon as possible. OCSP and CRLs are both mechanisms by which CAs can communicate certificate revocation information, but CRLs have significant advantages over OCSP. Let’s…
Let’s Encrypt had a great year in 2018. We’re now serving more than 150 million websites while maintaining a stellar security and compliance track record. Most importantly though, the Web went from 67% encrypted page loads to 77% in 2018, according to statistics from Mozilla. This is an incredible rate of change! We’d…
When we look at the general security posture of Let’s Encrypt, one of the things that worries us most is how much of the operating system and network infrastructure is written in unsafe languages like C and C++. The CA software itself is written in memory safe Golang, but from our server operating systems to our…
When you request a certificate from Let’s Encrypt, our servers validate that you control the hostnames in that certificate using ACME challenges. For subscribers who need wildcard certificates or who prefer not to expose infrastructure to the public Internet, the DNS-01 challenge type has long been the only choice…
Let’s Encrypt had a great year in 2017. We more than doubled the number of active (unexpired) certificates we service to 46 million, we just about tripled the number of unique domains we service to 61 million, and we did it all while maintaining a stellar security and compliance track record. Most importantly though…
Let’s Encrypt has reached a point where we’re ready to announce our launch schedule. First certificate: Week of July 27, 2015 General availability: Week of September 14, 2015 We will issue the first end entity certificates under our root under tightly controlled circumstances. No cross-signature will be in place yet…
We’re excited that support for getting and managing TLS certificates via the ACME protocol is coming to the Apache HTTP Server Project (httpd). ACME is the protocol used by Let’s Encrypt, and hopefully other Certificate Authorities in the future. We anticipate this feature will significantly aid the adoption of HTTPS…
Today we turned off our Online Certificate Status Protocol (OCSP) service, as announced in December of last year. We stopped including OCSP URLs in our certificates more than 90 days ago, so all Let’s Encrypt certificates that contained OCSP URLs have now expired. Going forward, we will publish revocation information…
Let’s Encrypt is proud to introduce Sunlight, a new implementation of a Certificate Transparency log that we built from the ground up with modern Web PKI opportunities and constraints in mind. In partnership with Filippo Valsorda, who led the design and implementation, we incorporated feedback from the broader…
The keys and certificates that will underlie Let’s Encrypt have been generated. This was done during a key ceremony at a secure facility today. The following objects were created: Key pair and self-signed cert for the ISRG root Key pair and certificate for the ISRG root’s OCSP Key pairs and certificates for two Let’s…
On a normal day Let’s Encrypt issues nearly two million certificates. When we think about what essential infrastructure for the Internet needs to be prepared for though, we’re not thinking about normal days. We want to be prepared to respond as best we can to the most difficult situations that might arise. In some of…
Update: January 15, 2026 Six-day and IP address certificates are now generally available. See 6-day and IP Address Certificates are Generally Available for details. This year we will continue to pursue our commitment to improving the security of the Web PKI by introducing the option to get certificates with six-day…
Every night, right around midnight (mainly UTC), a horde of zombies wakes up and clamors for … digital certificates! The zombies in question are abandoned or misconfigured Internet servers and ACME clients that have been set to request certificates from Let’s Encrypt. As our certificates last for at most 90 days…
Let’s Encrypt will enter Public Beta on December 3, 2015. Once we’ve entered Public Beta our systems will be open to anyone who would like to request a certificate. There will no longer be a requirement to sign up and wait for an invitation. Our Limited Beta started on September 12, 2015. We’ve issued over 11,000…
Since its inception, Let’s Encrypt has been sending expiration notification emails to subscribers that have provided an email address to us via the ACME API. This service ended on June 4, 2025. The decision to end the service is the result of the following factors: Over the past 10 years more and more of our…
Let’s Encrypt will be reducing the validity period of the certificates we issue. We currently issue certificates valid for 90 days, which will be cut in half to 45 days by 2028. This change is being made along with the rest of the industry, as required by the CA/Browser Forum Baseline Requirements, which set the…
NGINX and Let's Encrypt share a common vision of an open and secure web. Now, with built-in support for ACME, the world's most popular web server, reverse proxy and ingress controller for Kubernetes can simplify certificate management for everyone. From the home lab to scaled-out, mission-critical enterprise…