→ Coolors: Hit the space bar to generate a color scheme. Change the value of a color, lock it and hit the space bar to generate another color scheme based on the colors you locked. Once you are happy with the palette you created, export it or save it. You can also browse through palettes created by other users. Complete and user friendly!
→ Adobe Color CC: You can browse, build & share color schemes. You can log in to save and edit the color scheme you created. You can even get a color scheme from a photo you upload. Complete and versatile!
→ 0 to 255: Simple tool, which allow you to find colors in the same spectrum as another.