If you've been a regular user of PaperRater, then you may already be aware that we've been struggling with issues in the plagiarism detection module. We first ran into problems when using a 2nd-tier search API that powered this feature, but we were able to switch to Google and restore service. This was great for a time, but led to even worse problems as Google accidentally killed our subscription at one point, and, more recently, they have set a very low limit on API requests, which has caused our plagiarism check to have issues later in the day, while working flawlessly in the mornings.
After temporarily disabling the plagiarism check for the past few days, we are rolling it out again today with the Bing Search API powering it under the hood. We hope this will yield better uptime, but we have already found bugs with their phrase queries, about which we've contacted them. Feel free to contact us with any feedback regarding this rollout. Thank you for the patience you've shown as we continue to work through these issues. And please continue to spread the word about this free resource. Our team is working hard to deliver a top-notch product that is accessible to all. But all funds are currently devoted to development and operations, so we need your help to spread the word! Linking to our website wouldn't hurt either. :-) Thanks!
UPDATE Nov. 10, 2013: We received a lot of feedback in the few days after this was posted (thank you!). We responded to this feedback by making further enhancements to the plagiarism detection, which we released near the end of this week. Results are not optimal, but the dissatisfaction rate has dropped significantly. We will continue to rollout other enhancements to the plagiarism checker in the weeks ahead that should help address accuracy.