Who Runs Let's Encrypt and What Other Projects Does ISRG Operate?
Let's Encrypt is a project of the Internet Security Research Group (ISRG), a 501(c)(3) public benefit organization focused on making the Internet more secure and private. ISRG also operates two sibling projects alongside Let's Encrypt, and its annual report is the best place to see progress across all of that work.
The organization behind Let's Encrypt
ISRG is a nonprofit. That structure matters for how Let's Encrypt works in practice: the certificates are free, and the stated purpose is broad access to HTTPS encryption rather than a commercial product.
Let's Encrypt describes itself as "a Certificate Authority that provides free TLS certificates, making it easy for websites to enable HTTPS encryption and create a more secure Internet for everyone." The homepage frames the scale of that mission as "a nonprofit providing free TLS certificates to more than 700M websites."
So the chain of responsibility is:
- ISRG — the nonprofit parent organization, a 501(c)(3) public benefit organization.
- Let's Encrypt — a project operated by ISRG, acting as a Certificate Authority issuing free TLS certificates.
- Two sibling projects — also operated by ISRG, alongside Let's Encrypt.
What ISRG operates besides Let's Encrypt
The homepage states directly that "Let's Encrypt has two sibling projects" and that "Let's Encrypt and these two projects are operated by Internet Security Research Group (ISRG)." The page groups this under a section titled "More ways we're improving security and privacy," which is the framing ISRG uses for its wider portfolio: the goal is not only certificate issuance but security and privacy improvements more generally.
The source material confirms the existence and ownership of these two sibling projects but does not name them on the homepage. If you need the specific project names and what each one does, the annual report and the linked project pages are the places to look rather than the homepage summary.
How to follow ISRG's work
The 2025 Annual Report is presented as the main overview: "Our 2025 Annual Report highlights the progress we've made toward a better Internet." That is the most direct route to understanding what ISRG has been doing across Let's Encrypt and its sibling projects.
Other entry points on the site:
| What you want | Where to go |
|---|---|
| Overall progress and impact | 2025 Annual Report |
| How certificates are issued, plus best practices | Documentation |
| Recommended automation tools | ACME Clients |
| Technical help and discussion | Let's Encrypt Community forum |
| Ongoing announcements and engineering notes | The blog |
The blog is worth noting because it covers work beyond routine certificate issuance. Recent posts shown on the homepage include an engineering write-up on building a data warehouse with ClickHouse, a post on preparing certificates for a post-quantum future through an approach called Merkle Tree Certificates, and a historical piece about ISRG Root X1. Together they show the range of what ISRG treats as part of its security and privacy mission.
Funding and why the nonprofit status is relevant
The homepage ties ISRG's work to donations and sponsorship: "Your donation helps keep Let's Encrypt free and accessible to millions of websites around the world," and companies "who rely on or value our work to encrypt the Web can financially support Let's Encrypt." The section is headed "Global impact made possible by generosity."
That is the practical link between the two questions. Let's Encrypt is free to use because ISRG is a nonprofit funded by donations and sponsors, not because certificates are a loss-leader for a paid product. If you want to know who runs Let's Encrypt, the answer is ISRG; if you want to know what else that organization does, the answer is two sibling projects plus ongoing security and privacy work, documented in the annual report.