Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
Color Blindness Simulator
Simulate how colors appear to users with protanopia, deuteranopia, and tritanopia color blindness.
Color Blindness Simulator
Normal Vision
Reference
Protanopia
Red-blind (1% male)
Deuteranopia
Green-blind (1% male)
Tritanopia
Blue-blind (rare)
HEX: #ff0000
- Enter a color — Type a hex code or RGB value, or use the color picker, or adjust RGB sliders.
- Compare simulations — See how the color appears with normal vision, protanopia (red-blind), deuteranopia (green-blind), and tritanopia (blue-blind).
- Design accessibly — Use the simulation to ensure your color choices are distinguishable by users with color vision deficiencies.
What is Color Blindness Simulator?
A Color Blindness Simulator uses mathematical models of cone cell deficiencies to approximate how colors appear to individuals with different types of color vision deficiency (CVD). It applies transformation matrices based on the LMS (Long, Medium, Short wavelength) cone response model.
About 8% of men and 0.5% of women have some form of color blindness. This tool helps designers and developers create accessible color schemes by simulating the three most common types: protanopia (reduced red sensitivity), deuteranopia (reduced green sensitivity), and tritanopia (reduced blue sensitivity).
What is the difference between protanopia, deuteranopia, and tritanopia?
Protanopia is reduced sensitivity to red light (L-cones missing), deuteranopia is reduced sensitivity to green light (M-cones missing), and tritanopia is reduced sensitivity to blue light (S-cones missing). Protanopia and deuteranopia are the most common forms.
How accurate is the simulation?
The simulation uses the Brettel-Vienot-Mollon algorithm, which is a well-established scientific model for LMS-based color vision deficiency simulation. While not perfect for every individual, it provides a reliable approximation for accessibility testing.
Is this tool free?
Yes, it is completely free with no limitations. All processing happens locally in your browser.
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