Here’s a 16-color rainbow palette that provides good contrast with black text, making it suitable for spreadsheet highlighting:

json
{
  "palette_name": "16-Color Rainbow Palette",
  "colors": [
    {
      "name": "Red",
      "hex_code": "
          
          #FF0000
       "
    },
    {
      "name": "Orange",
      "hex_code": "
          
          #FF7F00
       "
    },
    {
      "name": "Yellow",
      "hex_code": "
          
          #FFFF00
       "
    },
    {
      "name": "Chartreuse",
      "hex_code": "
          
          #7FFF00
       "
    },
    {
      "name": "Green",
      "hex_code": "
          
          #00FF00
       "
    },
    {
      "name": "Spring Green",
      "hex_code": "
          
          #00FF7F
       "
    },
    {
      "name": "Cyan",
      "hex_code": "
          
          #00FFFF
       "
    },
    {
      "name": "Azure",
      "hex_code": "
          
          #007FFF
       "
    },
    {
      "name": "Blue",
      "hex_code": "
          
          #0000FF
       "
    },
    {
      "name": "Violet",
      "hex_code": "
          
          #7F00FF
       "
    },
    {
      "name": "Magenta",
      "hex_code": "
          
          #FF00FF
       "
    },
    {
      "name": "Rose",
      "hex_code": "
          
          #FF007F
       "
    },
    {
      "name": "Peach",
      "hex_code": "
          
          #FFB07F
       "
    },
    {
      "name": "Light Yellow",
      "hex_code": "
          
          #FFFF7F
       "
    },
    {
      "name": "Light Green",
      "hex_code": "
          
          #7FFF7F
       "
    },
    {
      "name": "Light Blue",
      "hex_code": "
          
          #7F7FFF
       "
    }
  ]
}

This palette captures a vibrant rainbow spectrum while ensuring that each color is bright enough to provide a good contrast ratio with black text, making it ideal for highlighting in spreadsheets.

Would you like assistance with anything else, like specific applications for this palette or tips on spreadsheet design?