BrightCarbon tested out three colour blindness simulators to help you improve the accessibility of your Google Slides presentations.

According to, 300 million people worldwide have colour vision deficiency (CVD). Up to 10% of your presentation audience maybe be affected by CVD, ignoring this could exclude members of your audience and negatively impact your outcomes. We know there’s no way you want to risk that! A good solution is to use a CVD simulator to check whether your presentation slides are accessible to people with CVD. CVD simulators mimic what it’s like to have CVD by placing filters on top of your screen to alter the colour. Once you can see the results, your can change colours and alter contrast to improve the accessibility of your Google Slides presentation. There are lots of CVD simulator options out there, and it’s not easy to know which is best – so we put a few to the test.

We’re comparing Colourblindly, Daltonize, and Let’s get color blind, three of the most downloaded and reviewed options on Chrome (available on other browsers too – more on that in just a moment!). We’re interested in their availability and functionality across different browsers, their features and how easy they are to use, and their privacy policies. It’s important to note that CVD varies between each individual, and so these simulators won’t give a 100% accurate depiction of what an audience member with CVD will see. That said, they are one of the best tools we have to mimic CVD for now and will help you improve the accessibility of your Google Slides presentations.

Browser availability

The three extensions are all free and available on the Google Chrome Web Store, meaning you can use them on both Google Chrome and Microsoft Edge as long as you have Chrome extensions enabled. Let’s get color blind is the only extension that’s also available on Mozilla Firefox. To download an extension , follow these instructions for Chrome, these instructions for Edge, and these instructions for Firefox.

The easiest way to access these extensions is to keep them pinned in your browser. To pin extensions that you’ve downloaded in Chrome, select the small jigsaw icon to the right of your URL bar, then click the pin icon of the extension you want to pin. The pin will turn blue. In Edge, the process is the same, except instead of a pin you’ll see an eye icon; you should click the eye icon so the eye is open.

For users that prefer Firefox or Safari to Google Chrome, there are built in options available. This means you don’t have to download an extension at all. Instead, simply open your presentation in Google Slides, right click on your Slides page near the title (if you click on the slide, the correct menu won’t appear) and select Inspect. In the pop up, select the Accessibility tab and select a form of CVD from the dropdown menu. Safari users also have in-browser accessibility options. Go to System Preferences then Accessibility, then select an option under Vision.

Google Slides accessibility extensions: Functionality and features

Now that we’ve covered how to download and access the simulators, let’s take a closer look at how easy they are to use.


Colorblindly has a simple menu allowing you to select different forms of CVD to simulate. There are 8 different settings and, when you’ve selected one, the colours on the menu title change in real-time. Colourblindly’s interface is pretty simple and the simulation in-menu is very handy.

screenshot of colourblindness simulator Colorblindly


Daltonize’s menu is even simpler, with 6 options. Unlike the other two extensions, it doesn’t explain the types of CVD which does make using this extension a little confusing.

screenshot of add-in Daltonize

Let’s get color blind

Let’s get color blind allows you to simulate the 3 main forms of CVD and it offers actual daltonization (a simulation for people with CVD to see in full colour). There are two sliders to adjust the strength of the simulation or daltonization. This is a feature the other two extensions don’t have but we’re not sure it’s that useful for checking your slides. There’s also an option to apply the filters to just the images on your screen – this option doesn’t work on Slides (or Docs, or Sheets) when we’ve tried it out in Chrome but works on webpages like news websites. A slight downside is that Let’s get color blind doesn’t offer monochromacy simulation.

screenshot of Google Slides accessibility add-in Let's get color blind

Of course, the user interface is only one part of what makes a good simulator. The functionality is equally, if not more important. When we tested these extensions, Let’s get colorblind was the only one that worked on Slides across all three browsers consistently. The results using the daltonization filter from Let’s get colorblind varies depending on the ‘severeness of each individual’s condition,’ so we can’t attest to its effectiveness. Neither Daltonize nor Colourblindly worked on Slides using the Chrome browser, we had to refresh the page a lot, but they worked on other webpages on Chrome. Daltonize and Colourblindly do work reliably in Google Slides using Edge as a browser.

Data safety

A key consideration when installing any extension is whether or not it collects your personal data. Daltonize’s publisher hasn’t provided information about whether they collect or use your data, so we don’t recommend that you download it if you’re privacy conscious. Let’s get color blind and Colorblindly both say that they ‘will not collect or use your data’. This means your data isn’t sold to third parties outside of the approved use cases, isn’t transferred for purposes unrelated to the core function of these extensions, and isn’t used to determine creditworthiness.

Our pick for improved accessibility in Google Slides

All the Google Slides extensions are easy to use but Colorblindly and Let’s get color blind have clearer privacy practices. Let’s get color blind seems a great option if you want an extension that simulates CVD to different extents and you’re a frequent user of the Chrome browser, as at times Colorblindly didn’t work on Slides. However, Colorblindly does have an in-menu simulator which helps you preview which form of CVD you are selecting. We find the visual cue that Colorblindly provides helpful, and also enjoyed the functionality of the sliders that Let’s get color blind uses!


We hope this has been helpful! If you’re new to Slides, a good place to start is our all-encompassing guide. If you’re looking for other tools to improve accessibility in Google Slides, then check out our post on it here! For tips on designing CVD-friendly presentations and visualisations, follow these links.

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Juliet Patrick

Communication consultant

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May 2024

Google Slides templates are a great starting point to improve the look and feel of your presentation. They’re fab as they’re accessible and low cost, but it’s important to remember that even well-designed presentations can be ineffective if the content is text heavy.

May 2024

Google Slides templates are a great starting point to improve the look and feel of your presentation. They’re fab as they’re accessible and low cost, but it’s important to remember that even well-designed presentations can be ineffective if the content is text heavy.

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