This is a 1-to-1 copy of the Keepa.com extension, but with the extra permission of "Access your data for all websites".
This extension will probably turn rogue someday with an update.

exactly what i need. waiting for the right moment saved me quite some money

Access all the websites you visit instead of just Amazon websites, so they track all your web activities and sell your data.

This does exactly what is promised, the charts are easy to read and very useful