GTmetrix is a free tool that analyzes your page’s speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers actionable recommendations on how to fix them.
What’s My DNS? – Instantly check your domain names current IP address and DNS record information against multiple name servers located in different parts of the world.
Pingdom – Monitor your website’s availability and performance for free with Pingdom and always be the first to know when your website is down. No installation required.