Testim - Stable, self-healing, end-to-end test automation via machine learning. Testim helps accelerate the delivery of high-quality software. Speed up test-authoring and improve the stability of automated, end-to-end tests.
intoDNS - IntoDNS checks the health and configuration and provides DNS report and mail servers report.
Ghost Inspector - Easily create automated browser tests for your websites and web apps. Ensure everything works and looks the way it should. No coding required. 14 day free trial!
Dnsstuff - DNSstuff offers DNS tools, Network tools, Email tools, DNS reporting and IP information gathering.
Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.
MxToolBox - All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.