Ross Woods, 2023
Some of these are free, and some are available only for a free trial for a limited time. You need to find the one that best suits your needs. (Links open new windows.)
PlagiarismCheck Check unlimited number of pages with no restrictions on word count.
DupliChecker Detects duplicate content and traces of copied content
Plagium Copy-and-paste content and results are displayed in seconds.
Paperrater Paperrater has three modules: checking grammar, suggesting writing changes, and detecting plagiarism.
Plagiarism Checker Shows results in a simple interface, marking the copied lines in red.
Others
quetext.com
plagiarismdetector.net
grammarly.com
Copyleaks.com
Copyscape.com
PlagScan (www.plagscan.com)