It's called Adobe Color CC. Registration is not required, but if you create an account you will be able to save your palettes.

Some explanation and in-depth info:

Occasionally, you might need to make a color scheme for some project, be it a PowerPoint presentation, a website or an app. However, this task can often turn out to be harder than it seems. It's not surprising since there's a whole field of knowledge called color theory which deals with which colors combine well and which don't.

Adobe Color CC simplifies this task greatly. First, you pick a desired "base" color. Then you select a "color rule", and then the tool will automatically fill in 4 other colors which will work well with yours. Also, you can simply upload a picture, and the tool will automatically pick a palette from it.

Another way to use it is when you don't want to open up a graphic editor like Photoshop and simply need a quick tool to work with color, get hex codes and so on.

Some clarification regarding the color rules, with examples:

• Analogous picks several similar colors to the one you select. The hue will vary, but just a little. Useful if you want to make a palette of similar, but slightly different colors.

• Monochromatic picks different shades of the same color—e.g., dark green, light green and so on. The hue will stay exactly the same.

• Triad picks a set of 3 colors which provide good contrast and look good together. Good for colorful projects.

• Complementary is similar, but it will pick just 2 colors, which provide will provide even higher contrast. Good when you want some color to stand out on a set background.

• Compound will pick 4 colors, 2 of which will have very high contrast, but the rest will just look decent with the others.

• Shades is very much like Monochromatic.

• And Custom allows you to adjust your palette as you wish, not sticking to any rules.

Finally, this tool is integrated into Adobe Creative Cloud, which might prove useful if you have it.