Classy icons crafted according to Microsoft guidelines. Available in PNG and SVG. Free for a link
ServerSuit - ServerSuit is a browser based program that enables remote Linux administration, monitoring, website hosting, and server setup automation.
Feather Icons - Simply beautiful open source icons
RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems
IconStore - Free icon packs by first-class designers
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.
Flat Icons - 20,000 unique, customizable icons with free lifetime updates