Software for comparing the standard text with a lot of texts from the catalog?

Question

Copywriting

The task is next.
There is a reference text .txt (in principle, any format). There is a directory with many .txt documents.
It is necessary to compare the reference text with the texts from the catalog, and determine the degree of "match" indicating the most similar files. Those. get some report: benchmark vs 1.txt (10% match), benchmark vs 2.txt (25% match) ... and so on. Where n.txt are text files from the directory.
PS. Yuzal Compare Suite PRO and Shingles Expert PRO are somewhere nearby, but not quite what you need.