- http://www.dev-books.com - Top of most mentioned books on stackoverflow.com.
- 30 Seconds of CSS - A curated collection of useful CSS snippets you can understand in 30 seconds or less.
- CSS reference - A free visual guide to CSS.
- CSS Cheat Sheet - A reference for CSS goodness.
- A free guide to <head> elements - A list of everything that could go in the head of your document.
- Choose an open source license - Help developers choose an open source license for their source code.
- List.community - Curated lists on Github.
- free-for.dev - This is a list of software (SaaS, PaaS, IaaS, etc.) and other offerings that have free tiers for developers.
- Dareboost - Quality and performance report.
- Yellow Lab Tools - Online test to help speeding up heavy web pages.
- GTmetrix - See how your site performs, reveal why it's slow and discover optimization opportunities.
- Observatory by Mozilla - How configure websites safely and securely.
- SecurityHeaders.io - Analyse the HTTP response headers.
- Web Server Security Test - High-Tech Bridge - Test web server security hardening, implementation of Content Security Policy (CSP) and other HTTP security headers.
- SSL Server Test by SSL Labs - Deep analysis of the configuration of any SSL web server.
- Webbkoll by http://dataskydd.net - This tool helps you check what data-protecting measures a site has taken to help you exercise control over your privacy.
- moz://a SSL Configuration Generator - An easy-to-use secure configuration generator for web, database, and mail software.
- Service Worker Cookbook - Collection of working, practical examples of using service workers in modern web sites.
- webhint - Linting tool that will help you with your site's accessibility, speed, security and more, by checking your code for best practices and common errors.
- What Web Can Do Today - Can I rely on the Web Platform features to build my app? An overview of the device integration HTML5 APIs
- Website Carbon Calculator - How is your website impacting the planet?
- Fat or Slow - Global Website Speed Profiler
- https://ipgeolocationapi.com/ - A free real-time IP to Geolocation JSON API with detailed countries data integration.
- https://uptimerobot.com/
- https://cunningbot.com