How to Block a Website on Firefox Desktop and Mobile

We show you how to block a website on Firefox using an add-on for the desktop browser and Apple's Screen Time tool.

While the sites we frequent tend to be high quality, the truth is that the internet is full of low quality, spammy, and even malicious content. It also has a lot of not-safe-for-work content that you may not want employees of younger members of your family to access. If you're a regular user of 's browser, then, it's incredibly useful to know how to block a website on and Mobile. This is what we're going to show you today.

Before we start, though, there's something important to note. At the time of writing, there's no in-built way to effectively block websites in Firefox . Instead, you'll have to install a third-party extension and allow it access to your browsing data.

If that makes you uncomfortable, we recommend you use a different browser on desktop and mobile, such as Opera.

With that said, here's how to block a website on Firefox desktop and mobile:

How to Block a Website on Firefox Desktop

Though you'll have to download a Firefox site blocker extension to close off websites, doing so is very easy and using one is simple. You can even block websites at certain times of day – for example blocking YouTube while you're working. Here's how:

  1. Install the Firefox block site addon

    Go to the Firefox add-on store and type “Block Site” in the search bar. The extension we'll be using is called Block Site by a user called Ray. We recommend you click it from the list and install it so you can follow along.

    Windows 10 - Firefox - Add-ons - Block Site

  2. Press “Add to Firefox”

    Windows 10 - Firefox - Add-ons - Block Site - Add to Firefox

  3. Click “Add” to accept the permissions prompts

    Windows 10 - Firefox - Add-ons - Block Site - Add to Firefox

  4. Press “Okay” to the “Block Site was added” prompt

    Windows 10 - Firefox - Add-ons - Block Site - Add to Firefox - Add - Okay

  5. Open your add-on settingsYou can do so by pressing the hamburger menu in the top-right and then clicking “Add-ons and themes”, or by pressing Ctrl + Shift + A

    Windows 10 - Firefox - Add-ons - Block Site - Add to Firefox - Add - Okay - More - Add-ons Appears

  6. OR: type “about:addons” in your URL bar

    Windows 10 - Firefox - aboutaddons

  7. Click “Extensions” in the right sidebar

    Windows 10 - Firefox - aboutaddons - Extensions

  8. Press the three dots next to the Block Site Firefox extension

    Windows 10 - Firefox - aboutaddons - Extensions - Three dots Block Site

  9. Click “Options”

    Windows 10 - Firefox - aboutaddons - Extensions - Three dots Block Site - Options

  10. Enter the website you want to block in the “Add a rule” field and press “Add”You can also adjust the blocking schedule if you wish to block sites on certain days and times.

    Windows 10 - Firefox - aboutaddons - Extensions - Three dots Block Site - Options - Add a Site

  11. Scroll to the “Tools” section and press “Save Options”

    Windows 10 - Firefox - aboutaddons - Extensions - Three dots Block Site - Options - Add a Site - Save

  12. Try to access the blocked siteIf your Firefox website blocker is working correctly, you should get the following message:

    Windows 10 - Firefox - aboutaddons - Extensions - Three dots Block Site - Options - Add a Site - Save - Result

How to Block a Website on Firefox Mobile

The method to block a website on Firefox mobile is a little different. If you're on you can add a free extension called Leechblock NG to your mobile browser. It works much the same as Site Blocker above.

If you're on iOS or iPad OS, you can use the built-in Screen Time tool instead. Just bear in mind that this will block sites on all browsers, not just Firefox. It will also apply to any device using your iCloud account, so be wary. Here's how you can use it:

  1. Open Settings and press “Sceen Time > Content and Privacy Restrictions”Toggle on the option that says “Content & Privacy Restrictions” and press the “Content Restrictions” heading below.

    Android - Leechblock NG - Content & Privacy Restrictions - Content Restrictions

  2. Tap on the “Web Content” heading in the content restrictions list

    Android - Leechblock NG - Content & Privacy Restrictions - Content Restrictions - Web Content

  3. Tap “Limit Adult Websites” and Press “Add Website” under the “Never Allow” heading

    Android - Leechblock NG - Content & Privacy Restrictions - Content Restrictions - Web Content - Limit Adult Websites - Add Website

  4. Type the URL of the website you want to block and press “Done”When you try to visit the website, you should now get the notification that it has been blocked.
    Android - Leechblock NG - Content & Privacy Restrictions - Content Restrictions - Web Content - Limit Adult Websites - Add Website - Url - Done

How to Change Default Search Engine and Clear Cookies/Cache

Now that you know how to block a website on Firefox, you may want to change some other aspects of your browser. While you're here, feel free to view our guides on how to change default search engine and how to clear cookies, cache, and site data.

Featured - How to Change the Default Search Engine of Your Browser