Thanks for letting me know. Yes, I'm using CloudFlare, for its trivial SSL, DDOS protection, and caching. I have CloudFlare's DDOS protection (the thing that

Thanks for letting me know. Yes, I'm using CloudFlare, for its trivial SSL, DDOS protection, and caching. I have CloudFlare's DDOS protection (the thing that causes captchas) set to "Essentially Off", the lowest available setting on their free plan. I just tried to query https://api.ctwatch.net/domain/ycombinator.com https://api.ctwatch.net/domain/ycombinator.com multiple times, each on multiple Tor circuits, but was unable to trigger the CloudFlare captcha. Did you see the captcha on my site, or is it just that you've noticed captchas on some other CloudFlare sites? I can look into setting up a Tor hidden service, which'll allow Tor users to bypass CloudFlare, if CloudFlare is actually causing issues.