For the sake of writing something, I’d like to share a few nice ressources. Modern designs include fancy flat color palettes, trendy gradients, or shiny patterns, so here are a few tools I check when looking for inspiration :
UI Gradients has a lot of gradients presets, all looking really good. You can add yours by submitting a pull request on the github repo .
Shade is a really nice tool giving you a lot of control with spread and color settings, and you can specify a base color.
Trianglify Generator creates a nice background that you can export as SVG (where you can customize the colors / strokes etc) or PNG. A bit more control over the colors would be nice !
You probably already know it. If not, go check it out !
“Curated collection of beautiful colors, updated daily.”
The CSS3 color code names, with equivalent rgb and hexa codes.
The Material Design color styleguides, from Google Material Design guidelines. You can find nice color associations here, and easily combine a vibrant primary color with a secondary hue.
So this should help you get nice modern colors for your next app, hope this helps !