As suggested by Biray Seitz on our Ryver "Third Party Tools" Chat, This one stems from the thread Alternative to Turnitin? where it was discussed what people's experience was with various Plagiarism checking LTI's.
Our University is in the process of looking at other Plagiarism Checkers and here are the majority that we've found through EduApp Center and through discussion threads here on the Community.
Here is what we have for research and resources so far:
They're all paid applications that were mentioned in comment thread of the Alternative to Turnitin? Discussion.
(9/28/2017: this document has been edited for consistency with my institution and our Plagiarism needs within Canvas. This has also been updated to reflect more recent company logo changes with the list above vendors)