I bought a lot of tools from Appsumo (just check how many deals I bought above this line) and this is one of the best purchases. Among content optimizers, I have used Marketmuse, Frase, Neuron Writer & ContentPace. Dokey offers several tools in one:

1) Content Optimizer - has a splendid visual element to show you if a word is under, overutilized or it appears the right number of times. The quality of the optimizer seems to be on par with Frase and Neuron and better than ContentPace.
2) Keyword research tool - this tool is based on SemRush data, so you are getting access to a very solid and reliable dataset
3) Content Strategy - Dokey connects to Google Search Console and, based on your own data, provides you the pages that - when optimized - will have the highest impact on your traffic. This is an amazing feature and my main reason for purchasing this tool
4) Internal linking - this particular module is worth $80 if you were to buy a dedicated tool

The value provided by Dokey is insane, and I consider this one of my best purchases on Appsumo. The team who developed it is an SEO agency, and the reviews on Trustpilot are stellar. I took the time to read all of them, and I am convinced Dokey is one of the deals that - a few years down the road - I will be very glad I bought.

Conflict of interests: I have no affiliation with Dokey and no conflict of interests. My recent video call with Bastien and my experience with the product convinced me this tool is a true hidden gem.