Let's Encrypt

Let's Encrypt is a free, automated, and open Certificate Authority (CA) run by the nonprofit Internet Security Research Group (ISRG) that provides TLS certificates to enable HTTPS for websites worldwide.

🚀 Overview

Let's Encrypt eliminates the barriers to HTTPS adoption by providing free, automated TLS certificates that are easy to obtain and renew, solving the problem of costly and manual certificate management that previously hindered web security.

It is built for website operators, developers, hosting providers, and organizations of all sizes who want to secure their sites without ongoing costs or complexity.

ISRG launched it in 2016 to create a more secure Internet by making encryption ubiquitous and frictionless, backed by donations and sponsors.

✨ Key Features

Free TLS/SSL certificates valid for 90 days (with support for shorter 6-day certs), automatically renewable via ACME clients to minimize management overhead.
ACME protocol for automated issuance and validation using challenges like HTTP-01 and DNS-01, compatible with numerous clients including Certbot.
Scalable infrastructure handling hundreds of millions of domains and certificates weekly, with features like wildcard support, IP address certs, and ACME Renewal Information (ARI).
Upcoming: Continued enhancements to ACME protocol, shorter lifetimes, and CRL support replacing OCSP.

🛠 Tech Stack

Frontend: Hugo (static site generator for the website)
Backend: Go (Boulder, the ACME-based CA software)
Database: PostgreSQL, Redis
Auth: ACME protocol
Hosting: ISRG infrastructure with CDN

👥 Who Is This For?

This project is useful for:

Developers who want to quickly enable and automate HTTPS on servers
Teams looking for scalable, cost-free certificate management
Indie makers building secure web apps without cert expenses

📸 Screenshots / Demo

Live demo: https://letsencrypt.org
GitHub: https://github.com/letsencrypt

🔥 Project Status

🟢 Actively building

Last updated: 2026-03-24

❓ FAQ

Is this project free?

Yes (completely free for issuing and using certificates; funded by donations).

Is the source code available?

Yes — https://github.com/letsencrypt (Boulder CA, website, Pebble test server, etc.); Certbot client at https://github.com/certbot/certbot

Can I contribute?

Yes — open source contributions via GitHub PRs/issues on repos like Boulder; feedback on https://community.letsencrypt.org/; financial support via donations https://letsencrypt.org/donate/ or sponsorships.