I built a free Email Authentication Checker that runs entirely in your browser

I kept using 3 different sites just to check SPF, DKIM, and DMARC for a single domain. It was slow, most of them are covered in ads, and I was never sure what data they were keeping.
So I built one tool that checks all three at once using DNS-over-HTTPS via Cloudflare's public resolver. Nothing goes to any server I control. You paste a domain, it returns the raw records and a plain-English explanation of what each one means.
It also tells you if something is missing and what a basic fix looks like.
Link: it-toolskit.org/tools/email-auth-checker
I have 21 other free tools on the same site — subnet calculator, security headers analyzer, robots.txt tester, JSON formatter, and more. All run in the browser, no signup, no tracking.
Built the whole thing as a static site on Cloudflare Pages. Happy to answer questions about how any of the tools work technically.