rubular - A ruby based regular expression editor

Turnitin - Turnitin is preferred by educational institutions around the world for preventing plagiarism. Instructors at all levels of education can request that students use the service to submit papers, and Turnitin checks those papers for plagiarism.

RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.

Unicheck - The plagiarism checker Unplag scans across the internet, repositories, open sources content and databases. It delivers real-time results and has no cached data.

RegEx Generator - RegEx Generator is a simple-to-use application that comes with the brilliance of intuitive regex and is also helping you out to test the regex.

PlagScan - The Internet makes plagiarism a bigger problem than ever.