benj moore dot com (spell out first name), sherw Willms (have to use proper spelling).
If you google a paint manufacturer's name, then navigate the site. Benj. Moore has a very easy to use one that doesn't require any downloading and you can "save" your "project file" then return later. Keep in mind that the colors that go together on your "monitor" may not look as attractive as they do on your home and vice/versa. I usually use for a "visual" match first for "curb appeal" on the IDEAS of what colors I might combine, but the actual Hues you really must test on your home, and see in the differing lighting conditions of the day and weather/clouds, etc. before you go "hog wild" and start having them mix up gallons and gallons of the stuff.
Best of luck and have fun "playing" with the project viewers.