Gradient by ShopFactory is a great tool for finding wonderful gradients, to use in your next project. It allows you to manipulate the gradients based on color, pigment and lightness.
The super fast color schemes generator! The Coolors app allows you to create, save and share perfect color palettes in seconds!
uiGradients is a community contributed collection of beautiful multi-color gradients, free to use on your next UI or design project.
Color Hunt is a free and open platform for color inspiration with thousands of trendy hand-picked color palettes.