I wanted to build something that did a few things I thought were important:
1. Be fast, and give a solid technical SEO analysis without dragging it out. 2. Create a way to share links directly to a site's results, with the share OG image previewing the actual score. 3. Offer everything through an API. You can inspect the calls made on the page to see it. I haven't documented it yet, but it's available to use.
The deepest checks we do right now are making sure your www and non-www setup redirects correctly, and looking across your site for any redirect chains that should be flattened. Alongside that, it covers the other basic technical SEO checks that matter for ranking — title tags, meta descriptions, headings, canonical tags, viewport, HTTPS, Open Graph tags, image alt text, structured data, and response time.
Looking for feedback on what checks would be helpful to add, but want to keep it fast and lite.