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What are Safari Extensions?

Safari Extensions are just browser extensions for the Safari web browser. Browser extensions are apps that customize the way your web browser works.

The internet is an exciting place to visit. Some would say you can practically live online. Still others are proclaiming that the future of the internet is a fully three dimensional experience called the metaverse. Meanwhile, the primary way most of us will access the internet is through a modern web browser like Safari, Firefox, Google Chrome, or Microsoft Edge (RIP Internet Explorer1).

Browser extensions are small software applications that extend or add functionality to modern web browsers.

Approximately two out of every three people on earth have access to the internet — that’s about ~5 billion internet users! With such a massive user base, web browsers are carefully designed to make it as easy as possible for people of all skill levels to search the internet, visit websites, and access web applications for things like email and online banking. However, even with all of the combined investment of the largest companies in the world — including Apple, Microsoft, and Google — it’s simply not possible to offer built-in features to customize the browser experience for all 5 billion internet users. That’s where browser extensions come in.

What is a browser extension?

Browser extensions are small software applications that extend or add functionality to modern web browsers. Web browsers are like most modern software applications, they process and exchange information — “uploading” or “sending” data, and “downloading” or “receiving” data — over a vast interconnected network of systems (the internet). Browser extensions can modify the flow of the information being exchanged. Some of the most popular browser extensions add features like ad blocking, password management, grammar checking, coupon codes for online shopping, dark mode, and more.

What can browser extensions do?

Browser extensions can do almost anything that a browser can do, which is almost anything! They can protect your privacy by reducing the amount of data that websites collect. They can make decisions for you, like deleting annoying ads from web pages. They can remember things for you, like your passwords. They can modify the content you see on screen, like switching blindingly bright websites into “dark mode” at night time.

Some of our favorite browser extensions are:

  • The Magic Highlighter (oh hey, that’s us): find what you’ve been searching for ⚡️
  • 1Password: the best password manager 🔐
  • Grammarly: improves your writing ✍🏽
  • Honey: helps you find discount codes for online shopping 💰
  • Vinegar: YouTube cleaner 🍿
  • Noir: automatic dark mode 🌙

Why use browser extensions?

Browser extensions help you get the most value out of the internet by customizing your browsing experience. To illustrate, if you live somewhere or are planning to travel somewhere with lots of sunshine, you will likely wear sunglasses. 🕶️ Sunglasses not only make us look cooler2, they also protect our eyes from harmful ultraviolet (UV) light. But they effectively alter our world view in the process, causing everything we see to be a slightly darker shade than it would be without sunglasses. That’s basically the same thing as a browser extension that converts bright websites into “dark mode”. Browser extensions are like accessories for the browser in the same way that sunglasses are an accessory to your #OOTD.

Getting started with browser extensions

Most modern desktop browsers have marketplaces or online catalogs available where you can discover and install browser extensions. Firefox has Add-Ons. Google Chrome and other Chromium-based3 browsers have the Chrome Web Store. Safari Extensions come simply from the App Store.

Check out these App Store Stories — compiled by Apple itself — about getting started with Safari Extensions:

Pros and cons of browser extensions

You might be thinking that this all sounds great, so what’s the catch? Like anything in life there are of course pros and cons to installing browser extensions. The three primary considerations regarding browser extensions are: performance, privacy, and security.

  • Performance

    No one likes to interact with slow websites or web applications. Browser extensions can add additional processing steps during time sensitive data transmission and page loads, but a good browser extension should add functionality that saves time. For example, ad blocking browser extensions should reduce the amount of data that needs to be processed in order to load the page content, and The Magic Highlighter can help you locate information faster by annotating important content. Well-engineered browser extensions won’t introduce any discernable performance penalty, but not all extensions are created equally. If browser extension developers aren’t careful, they can add processing overhead and inadvertently slow down your browsing experience.

  • Privacy

    In order for browser extensions to function, they need permission to process the website and web application content we access from our web browsers. That’s probably not a concern when we’re reading Wikipedia, but what about when we’re browsing social media sites, accessing email, or even conducting transactions via online banking? The best kind of browser extension (from a privacy perspective) will process the data on-device, ensuring that your browsing history and other private information stays that way. The good news is, most modern web browsers help users make informed decisions about browser extension permissions, even enabling users to grant browser extension permissions on a per-website basis.

  • Security

    How many days hours has it been since you’ve seen a headline about a company who was hacked and had customer data stolen by some bad actor? When browser extensions need to collect data and/or send data to remote services (including third-party services) in order to provide some functionality, it introduces risk. Even if data is only collect on-device, is it stored securely so as to prevent unauthorized access? If the browser extension is open source you might be able to answer these questions for yourself, otherwise a third-party (e.g. a tech reviewer) might be able to vouch for its integrity. Look at the download statistics and reviews. Does the developer have a good reputation?

Browser extension best practices

The ABC’s of staying safe and having a good time with browser extensions are: A) Always use the App Store (only install browser extensions from a trustworthy source). B) Beware of overbearing permissions requests (review how app developers handle your data via the App Store permissions summary). And C) Consider the source of the browser extension… does the developer have a good reputation. Apple’s own guide on getting Safari Extensions encourages users to click an app’s name or icon (in the App Store) to get a description, view customer ratings and reviews, and see the app’s privacy practices.

I am human

Last but not least, familiarize yourself with your browser’s extension settings menu so you know how to review which browser extensions you have installed, and disable or uninstall browser extensions you no longer need or trust. For Safari users, check out the support documents for Changing Extension settings in Safari on Mac and Getting extensions to customize Safari on iPhone.

Mobile browser extensions

Google Chrome is the most popular web browser in the world4. It has supported browser extensions since 2009–10 so it’s probably no surprise that it has an extensive catalog of browser extensions available via the Chrome Web Store. However you might be surprised to learn that browser extensions are not yet supported in Google Chrome for Android, the default web browser on the most popular operating system in the world4.

Safari on iPhone is the first [built-in] mobile device web browser in the world with support for browser extensions.

Meanwhile, Apple has quietly beat Google to market by introducing support for mobile browser extensions in iOS 15 (and Safari 15.0) in September 2021, making Safari on iPhone the first [built-in] mobile device web browser in the world with support for browser extensions. Apple has continued to improve on the mobile browser extension experience with new extension APIs and browser extension sync in iOS 16. Safari 16 makes it easy to deliver cross-platform (phone, tablet, and desktop) browser extensions like The Magic Highlighter.


Browser extensions are fun and useful! They help you get more done while you browse the internet. Safari extensions extend the browser extension value proposition one step further than the competition by supporting browser extensions on mobile.

If you found this blog post useful, you might enjoy The Magic Highlighter. It is available now as a Universal Purchase5 for iPhone, iPad, and Mac for just $1.99. We hope you give it a try and that it does a good job of introducing you to the wide world of browser extensions.


  1. Microsoft’s Internet Explorer was once so dominant it was called a monopoly, then relatively rapidly reached irrelevance, and is now officially no longer with us. But Internet Explorer was the first browser to introduce the concept of browser extensions over 20-years ago↩︎

  2. It’s true. It’s science. ↩︎

  3. Chromium is the name of the open-source core version of Google Chrome. ↩︎

  4. By market share. ↩︎ ↩︎

  5. No need to purchase separate apps for iOS and macOS – we give you both for the price of one! ↩︎

Get The Magic Highlighter TODAY

The Magic Highlighter is available on the App Store for iPhone, iPad, and Mac. Find what you’ve been searching for. ⚡️