Netumo - Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.

LinkChecker - LinkChecker is a free, GPL licensed website validator.

AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.

DRKSpiderJava - DRKSpider is an open source website crawler (sitemap generator) and link checker. Features:

RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems

Pulno - SEO Audit and Website Analysis. Pull up your SEO.