StackGrade grades any domain from 0 to 100 in a few seconds: SPF (including the 10-DNS-lookup limit), DKIM, DMARC, MX, website security headers (HSTS, CSP, clickjacking, cookies) and domain expiry/transfer lock. Each check comes with a plain-English fix and a copy-paste record. Free, no signup, and no backend: checks run in your browser using public DNS-over-HTTPS, registry RDAP and Mozilla HTTP Observatory. Single-check pages for DMARC, SPF, DKIM, security headers and email provider lookup, plus a free embeddable widget for agencies. Built by the GreenTools maker (that's me). Beta.
Solo builder behind GreenTools. Checking a domain's SPF, DKIM, DMARC, security headers and expiry meant hopping between several separate tools, so StackGrade puts them on one free page with a plain-English fix for each problem.