Nibbler - Free tool for testing how good your website is, and what you can do to improve it. Check accessibility, SEO, social media, compliance and more.
Pennywise - Cross-platform application to open any website or media in a floating window
tota11y - An accessibility visualization toolkit from Khan Academy
Zercurity - Monitor your infrastructure for policy non-compliance, live
Accessible Metrics - Digital Governance
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica