How to check the duplication of the extended version of the paper?

Question

One of my papers was accepted by the conference. I now want to write an extended version of the paper for submission to the journal.

The journal requirements are:

Extended versions of published conference papers are welcome, but they must have at least 40% new impacting technical/scientific material in the submitted journal version, and there should be less than 30% verbatim similarity as reported by a tool (such as CrossRef). Additionally, the conference papers and the detailed summary of differences must be included as part of the journal submission to TC.

Why can't I find the tool CrossRef? I want to use some other websites to check the duplication, but how can I check the duplication only compared to my conference papers?

Has anyone experienced something like this? what should I do?

Thanks

Answer 1

The tool referred to is the CrossRef Similarity Check. Only "CrossRef members" (i.e., mainly publishers) have access to it once they pay a special fee in return. In other words, the tool is not publicly available to you.

As regards a duplication-check you could conduct on our own, there are free text-comparison tools like this one where you can insert the two articles and see to which extent they overlap or differ from each other.

Here is an example (with a 68% match):

However, note that every text-comparison tool could spit out different results, simply because there is more than one way to calculate text similarities.