Certbot is EFF's tool to obtain certs from Let's Encrypt and (optionally) auto-enable HTTPS on your server. It can also act as a client for any other CA that uses the ACME protocol.

The easiest, and most secure way to access and protect all of your infrastructure.

Automatically provision and manage TLS certificates in Kubernetes

Let's Encrypt/ACME client and library written in Go

An open-source and free self-hosted SSL certificates ACME tool, automates the full-cycle of issuance, deployment, renewal, and monitoring visually. 完全开源免费的自托管 SSL 证书 ACME 工具，申请、部署、续期、监控全流程自动化可视化，支持各大主流云厂商。

ACME client implemented as a simple shell-script – just add water

Curated list of 20,000+ hours and 200+ free courses with certificates in IT, CS, Design and Business.

A native implementation of TLS in Javascript and tools to write crypto-based and network-heavy webapps

Websockify is a WebSocket to TCP proxy/bridge. This allows a browser to connect to any application/server/service.

🧰 A zero trust swiss army knife for working with X509, OAuth, JWT, OATH OTP, etc.

CAUTION: END OF SUPPORT ON 14 AUG 2026. The 'jsrsasign' (RSA-Sign JavaScript Library) is an opensource free cryptography library supporting RSA/RSAPSS/ECDSA/DSA signing/validation, ASN.1, PKCS#1/5/8 private/public key, X.509 certificate, CRL, OCSP, CMS SignedData, TimeStamp, CAdES and JSON Web Signature/Token in pure JavaScript.

Automated docker nginx proxy integrated with letsencrypt.

Tools to bootstrap CAs, certificate requests, and signed certificates.

Frida scripts to rewrite mobile applications at runtime to directly MitM all HTTPS traffic

obtain free SSL certificates from letsencrypt ACME server Suitable for automating the process on remote servers.

🔒 acmetool, an automatic certificate acquisition tool for ACME (Let's Encrypt)

a collection of scripts for MikroTik RouterOS

Professional ACME Client for Windows (and now cross-platform via Certify Management Hub). Certificate Management UI, powered by Let's Encrypt and compatible with all ACME v2 CAs. Used by over 150,000 organisations. Download from certifytheweb.com

Free, automatic HTTPS certificate generation for ASP.NET Core web apps

Custom Kubernetes controller that can be used to replicate secrets, configmaps and certificates.