A website builder tool receives an image(s) selected or uploaded by a user, performs color analysis on that image(s) to identify prominent colors and most-occurring colors, and suggests one or more color palettes for use on the website such that text and other visual elements on the website will be aesthetically compatible with the user-provided image(s). Additionally, the server selects images from a database of stock images based on color compatibility with the user-provided image. The process can be performed in the CIELAB color space. Images can also be selected in part based on subject-matter tags. The user thus uploads an image(s) for placement on his website and optionally provides subject-matter descriptive tags, and the website builder tool responds by suggesting additional images and a color palette that will be compatible with the user-provided image, thus making the process of building an attractive and consistently themed website faster and easier.