OpenSSL - OpenSSL is a free and open source software cryptography library that implements both the Secure Sockets Layer (SSL) and the Transport Layer Security (TLS) protocols, which are primarily used to provide secure communications between web browsers and …

Documize - Enterprise-grade wiki and knowledge management platform

Let's Encrypt - Let’s Encrypt is a free, automated, and open certificate authority brought to you by the Internet Security Research Group (ISRG).

HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.

Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.

ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.