I built a free DMARC/DKIM/SPF checker: https://dmarcchecker.app/. No usage limits, no ads—just a small footer link to one of my other projects. Made it for the exact reason you mentioned.
This is awesome. Thanks! Sensible, easy to use, easy to understand the results.
I've been trying the google one, for example, and it doesn't even work. "request timed out." Fishy, because yours works great.
much appreciated!