Success Criterion 1.4.1 - Level A
Use of Color
Ensure colour isn't the only way information is conveyed. Information which is conveyed only by colour cannot be perceived by everyone. For example, also use shape to give instructions, e.g. reference a green checkmark or red cross. Inside a legend, use numbers in addition to colour, to allow people who are colour blind to find what they are looking for.
Colour can be perceived less well by people who are colour blind or who are elderly.
Use a red cross or green check mark for feedback to make the feedback clear for people who do not perceive colour very well.
With a legend, use numbers in addition to colour so that people who are colour blind can also find what they are looking for.
Do not only use colour for required fields, but also add text so that blind or colourblind people perceive the field is required.
“Is all information on the screen also clear without the use of colour?“
This can be tested visually, no assistive technology is needed.
When designing an app, keep in mind that information is not conveyed through colour alone.