Awesome, thanks for the detailed feedback! As you can probably imagine, tweaking the rules to work with every imaginable website configuration is an ongoing process so this is super helpful.

> All the errors I'm getting on my site are due to the login-wall on some of the pages because it's detecting /account/login/?next=... links as internal redirects.

> "Use unique titles" / "Set page descriptions" / "Avoid URL parameters" / "Avoid thin content pages" / etc

Allowing Checkbot to login could help but I'll look into how to improve this.

> "Avoid inline JavaScript" -> I'm making quite a bit of use of the <script type="application/json" id="foo"/>

Ah, thanks, this is an easy fix. I'm planning to add structured data checks in the future as well because checking you've configured these correctly on all your pages is cumbersome.

> "Hide server version data" -> This is picking up "server: cloudflare" as an error. Means no site behind cloudflare will ever pass this which seems overkill.

Yes, for what it's worth this is defined as "low priority" internally and the rule description is written to emphasise this. I could change it to only fire when there's version numbers in the headers perhaps. I agree knowing you're using Cloudflare isn't a big deal but some servers will advertise very specific OS and PHP versions for example.

> "Use lowercase URLs" -> So, on my site you can access objects with IDs like youtube's (/id/vZEz7JoNnfgVo...). It's picking up all those as errors. Feels wrong?

Yes, I'll need to think how to avoid that case. It's a good general rule when you're writing human readable URLs however so I wouldn't want to disable it completely.

> UI: Not a fan of the "x inlinks / y outlinks / headers / recrawl / html / copy" links below the URLs on the results page. Low contrast, unclear what I'm clicking and where it's gonna take me. The "copy" button: What am I copying? (Clearly the URL as I tried it, but that'd be more useful as a clipboard button next to the URL for example)

Hmm, any more suggestions on what to change here? I made these links prominent because they were common user actions and added tooltips to them to help describe what they do. I agree it's not completely obvious what they do at first but there's only so much space available. I experimented with only showing these when you hover over a table cell. I do want to add more shortcuts in the future such as a quick way to look up a URL on Google or on archive.org so I'll likely have a "more" button for extra options later.

> Finally, I ran it on my company's blog and it ended up crawling a ton of the company's various exosites on different domains which wasn't super useful, especially since none of it showed up in the final results.

Can you give more details here? Checkbot will probe <a href="..."> links to check they're working for example but shouldn't spider sites that are considered external. I originally had it crawling subdomains of the start URL but changed that default because it wasn't what most people wanted.

> Shoot me an email (see profile) if you want to talk through some more feedback (especially UX feedback).

Great, let's keep in contact (see my profile as well)! Hopefully it's obvious UX is important to me too. It's been challenging to find a balance in showing the right amount of information on the screen while battling with the horizontal space constraints you get with long URLs. The "Avoid temporary redirects" report is a good example of this e.g. for each row, you want to know the redirect status code, the start URL, redirect destination and redirect path.