MAXMIND maintains an incredibly accurate geoip database.
Comprehensive domain configuration test built by Ivan Ristić.
Qualys SSL Labs
SSL/TLS testing for:
Email Message Header Analyzer
Format email message headers into an easily readable format.
Analyse all HTTP response headers from a website against current and emerging security best practices.
Content Security Policy (CSP) Evaluator
Test Content Security Policy (HTTP Response Header) configuration.
Code-Breaking, Cipher and Logic Puzzles solving tools.
Web app offering modular conversion, encoding and encryption online. Translations are done in the browser without any server interaction.