- Vischeck: Simulate how your images look for people with different forms of colorblindness (web-based)
- Color Oracle: Simulate how your images look for people with different forms of colorblindness (desktop-based, more types of colorblindness)
- Adobe Color: Create, share, and explore rule-based and custom color palettes.
- ColourLovers: Like Facebook for color palettes.
- viridis: Percetually uniform color scales.
- Scientific Colour-Maps: Perceptually uniform color scales like viridis. Use them in R with scico.
- ColorBrewer: Sequential, diverging, and qualitative color palettes that take accessibility into account.
- *HCL palettes: The colorspace package for R includes a ton of qualitative, sequential, and diverging HCL (hue-chroma-luminance) palettes that use fancy mathematical rules that maintain perceptual distance
- Colorgorical: Create color palettes based on fancy mathematical rules for perceptual distance.
- Colorpicker for data: More fancy mathematical rules for color palettes (explanation).
- iWantHue: Yet another perceptual distance-based color palette builder.
- Photochrome: Word-based color pallettes.
- PolicyViz Design Color Tools: Large collection of useful color resources
- Google Fonts: Huge collection of free, well-made fonts.
- The Ultimate Collection of Google Font Pairings: A list of great, well-designed font pairings from all those fonts hosted by Google (for when you’re looking for good contrasting or complementary fonts).
- Use the Creative Commons filters on Google Images or Flickr
- Noun Project: Thousands of free simple vector images
- aiconica: 1,000+ vector icons
- Vecteezy: Thousands of free vector images