Hi.
There's not accessibility for copy button. What if one doesn't use the mouse? -> Can't use this tool at all. Furthermore I don't think mouse-drag is good way to generate colors at all.
Where's custom color saving option? - Writing custom color on top where color is shown doesn't change the color at all - doesn't work for me (Using firefox).
Height under 824px and/or width between 1024px and 825px show weird page saying that "App works best in portrait mode" - super weird and not sure why is that implemented if mobile is.
Why is there, in the bottom left corner, IQ online test link?
Can't really say it's a good tool at all at this point and stating "There are plenty of options out there when it comes to online color picker tools, but we want to be the best." is pretty bold.
If you want to have the best tool among all others of the same kind, then you must offer more than your competition and/or at least same but in a better way for the user.
Here are my recommendations: w3schools.com/colors/colors_picker.asp htmlcolorcodes.com
Those instantly offer multiple color variations based on your color choice, some even generate decent color palette. Also, free.
Furthermore I have to commend on another statement of yours: "Choosing the right colors for a project is always tough, and we want to make that process as simple as possible"
Another thing to be aware of - Your app screen takes whole screen as a color. Very fast swapping between light and dark colors might have impact on people who could suffer from photosensitive epilepsy.
I think this tool has long way of improvements to go to be considered as one of proper tools to be chosen among all others.