Uppy - The next open source file uploader for web browsers
Image Color Summarizer - The web service provides statistics describing color characteristics of an image identified by URL.
Filestack - Simple file uploader and robust APIs for uploading, transforming, and delivering any file into your app. Filestack is a collection of tools and powerful APIs that make it simple to upload, transform, and deliver content.
Colllor - With Colllor it is much easier to generate a consistent color palette with just a few clicks.
Uploadcare - File uploading, media processing & content delivery for modern web apps
Color Palette Generator - Enter the URL of an image and find its color palette