The COT indicator seems to be too old for an indicator. Although, you can use in a metatrader, the problem with this indicator is that you need an external data to work with.
The one that I saw works with FXCM strategy trader. I think I found no problem with this except that I cant find any clue how to have this on a demo account with this FXCM strategy trader. I am not sure though but if my memory serves me right, it was released as a beta platform and from that on, I have no knowledge then about that.
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Good grief that I found one made who has been using COT indicator from easyforexexperts and he told me that every penny of $30 is worth it. This indicator was found in the book of William entitled Trading with Insiders. The book has a great collection of COT index, COT graph, open interest and more. The COT from this group is way easier than that of the metatrader. Why he considers this especially is the auto update feature. Using the COT report alone, he saw a bull market in Gold forming from a week of trading.