How to Block Websites and Adult Content in Firefox and Edge

Updated 12 Nov 2026

Version note: Checked on 8 Nov 2026 against Microsoft's Family Safety and Bing SafeSearch support pages, and Mozilla's Firefox support pages. Mozilla's site blocked direct access, so we read Wayback Machine copies of the Mozilla pages rather than the live pages. Those pages show "last updated" dates between 4/16/22 and 9/19/25, so menu names may have changed since. Microsoft's pages did not state a browser version for these steps.

What we could and could not confirm

We looked for an official Mozilla or Microsoft help page that describes a built-in website block list inside Firefox or Edge. We did not find one we could open, so this guide does not describe one. Instead it covers what the official pages do describe. If you only need a quick answer for Chrome, see our Chrome guide: How to Block Websites on Chrome (Windows, Mac and Chromebook).

Edge: Microsoft Family Safety filters

Microsoft says its web and search filters "work across any Windows, Xbox and mobile device that has the Microsoft Edge browser and Family Safety apps installed". The page lists Windows 11, Windows 10 and Xbox One under "Applies To".

Who it is for: Family Safety is built around a family group. Microsoft says "family members must use a supported browser while signed in to their Microsoft accounts". The page's wording is about protecting "yourself and your family", but its steps are written for choosing a family member. If you are the only person in the group, check Microsoft's own pages before relying on it.

Microsoft's steps for the web view:

1. Sign in to your Microsoft account.
2. Select Family Safety from the menu on the left.
3. Find your family member, then select Go to overview.
4. Select Edge as a platform.
5. Turn the Filter inappropriate websites and searches toggle on.

Microsoft says that by default "mature websites will be blocked and searches will be filtered in the Bing search engine". You can add URLs under Blocked Sites or Allowed sites. You can also limit access to specific sites only by turning on Only use allowed websites. In the Family Safety app, the path is to select your family member, select Content filters, and turn on the Only use allowed websites slider.

One feature matters for other browsers. Microsoft says that when the filter is on, "unsupported browsers are blocked so that filtering cannot be bypassed", and that "you can manually unblock a browser on the device". Its page says the supported browser is currently Edge. So the filter is designed to cover the browsers on the device, but a browser that has been manually unblocked is outside it.

Edge and Firefox: Bing SafeSearch

SafeSearch filters search results rather than blocking websites you type in directly. Microsoft's page "Turn Bing SafeSearch on or off" gives these steps:

1. Open a browser and go to Bing.com.
2. Select the icon in the upper right of the window, select Settings, then select More.
3. Choose your SafeSearch preference: Strict, Moderate or Off.
4. Select Save at the bottom of the menu.

A second Microsoft page explains the levels. Strict "filters explicit text, images, and videos out of your search results". Moderate "filters explicit images and videos, but not text", and Microsoft says it is the default. Microsoft also notes that "SafeSearch settings for Bing users under 18 may be automatically set to Strict" to comply with local law.

SafeSearch only applies to Bing searches. It does not stop someone using a different search engine or opening a site by its address. Our guide covers the setting for Google, Bing and others: How to Turn On SafeSearch on Google, Bing and YouTube.

Firefox: add-ons are made by other people

Mozilla's page on add-ons says extensions "add new features to Firefox or modify existing ones" and that "Community-created extensions can be found on addons.mozilla.org". That is the route for a website-blocking extension.

We do not name or recommend any. Extensions are third-party software, and what each one blocks, stores or asks permission for is up to its maker. Before installing one, read what permissions it requests and who made it. In our view, a blocking extension you install yourself is a speed bump rather than a lock, because you can also remove it yourself.

Firefox: secure DNS can interact with DNS filters

If you filter adult sites with a DNS filter on your network, Firefox's DNS over HTTPS (secure DNS) setting is worth knowing. Mozilla's page says some people and organisations "rely on DNS to block malware, enable parental controls, or filter your browser's access to websites. When enabled, DoH bypasses your local DNS resolver and defeats these special policies."

Mozilla adds that Firefox "allows users (via settings) and organizations (via enterprise policies and a canary domain lookup) to disable DoH when it interferes with a preferred policy". Its Default Protection level "disables DoH when VPN, parental control or enterprise policies are active or when a network tells Firefox not to use secure DNS". Mozilla says Increased Protection keeps DoH "constantly active with the provider you select".

To see which level your Firefox uses, follow Mozilla's steps:

1. Click the menu button at the upper right of the screen.
2. Click Settings.
3. Click Privacy & Security on the left.
4. Scroll down to the DNS over HTTPS section.

The canary domain is use-application-dns.net. Mozilla says network administrators may configure it "to signal that their local DNS resolver implements special features that make the network unsuitable for DNS-over-HTTPS". It applies only to people who have DoH enabled as the default option, not to people who "have made the choice to turn on DoH by themselves". So the canary domain is a signal for network settings, not something you toggle in Firefox.

For the setup of DNS filters, and how this differs on Chrome and Android, see our guide: Secure DNS and Porn Filters: When Encrypted DNS Helps and When It Bypasses a Filter.

The honest gaps

• One browser each. Edge's Family Safety filter and Firefox add-ons cover that browser. Other browsers, apps and a second device are not covered by them.
• Private windows and extensions. Mozilla's and Microsoft's pages do not say how these settings behave in every private window, so we make no claim either way.
• Family Safety is a family tool. Its filters assume a family group and Microsoft accounts.
• Search filters are not blocks. SafeSearch changes search results only.
• Willpower is still needed. Anything you can switch off in your own settings can be switched off in a hard moment.

FAQ

Can Firefox block a website without an add-on?

We could not find an official Mozilla help page describing a built-in block list, so we cannot say it does. Mozilla's page on add-ons describes extensions as the way to add features.

Does Edge have a built-in adult content filter?

Microsoft's Family Safety filter works with Edge for family group members, and by default blocks mature websites and filters Bing searches. Bing SafeSearch is a separate search setting.

Can I use Microsoft Family Safety just for myself?

Microsoft's page is written for family members in a family group. It does not describe a single-person setup, so check Microsoft's pages for your situation.

Does Firefox secure DNS stop a DNS filter from working?

Mozilla says DoH "bypasses your local DNS resolver" when enabled, but that Default Protection turns DoH off when parental controls are active or a network tells Firefox not to use it. Increased Protection keeps DoH active with the provider you select.

Where Mamori fits

The steps above are free and need no extra app. Their limit is that each covers one browser on one device, and Firefox add-ons rely on third-party software.

Mamori is a newer app for iPhone, iPad and Android, so it does not cover a computer. On a phone it blocks 2.5M+ adult sites across the whole phone, not just one browser, so Firefox, Edge or any other browser on that phone is covered. On Android it is an on-device DNS filter using Android's VpnService, with no remote VPN server, and it does not log browsing. On iPhone and iPad it uses Apple's Screen Time web content filter plus its own blocklist. It also forces SafeSearch on Google, Bing and other search engines.

Before protection can be switched off, you meet a cooldown timer, a random phrase, or a PIN or passphrase, and a trusted person can hold the PIN. When protection is off, everything is off and Mamori can be uninstalled normally. That is deliberate: the friction is the lock you chose in advance.

Honest limits: Android allows only one VPN at a time, so another VPN or blocker that takes the slot switches Mamori's filter off. Mamori has no accountability reports and does not replace support from people or a professional. There is a 7-day free trial on the monthly and annual plans, plus a one-time lifetime option. For a comparison of approaches, see: Website Blocker, App Blocker or DNS Filter: Which One Blocks What.

Related guides

Sources

• Microsoft Support, Filter websites and searches using Microsoft Family Safety: https://support.microsoft.com/en-us/family-safety/filter-websites-and-searches-using-microsoft-family-safety
• Microsoft Support, Turn Bing SafeSearch on or off: https://support.microsoft.com/en-us/bing/turn-bing-safesearch-on-or-off
• Microsoft Support, Blocking explicit content with SafeSearch: https://support.microsoft.com/en-us/bing/blocking-explicit-content-with-safesearch
• Mozilla Support, Firefox DNS over HTTPS (Wayback Machine copy): https://support.mozilla.org/en-US/kb/firefox-dns-over-https
• Mozilla Support, Configure DNS over HTTPS protection levels in Firefox (Wayback Machine copy): https://support.mozilla.org/en-US/kb/dns-over-https
• Mozilla Support, Canary domain use-application-dns.net (Wayback Machine copy): https://support.mozilla.org/en-US/kb/canary-domain-use-application-dnsnet
• Mozilla Support, Find and install add-ons to add features to Firefox (Wayback Machine copy): https://support.mozilla.org/en-US/kb/find-and-install-add-ons-add-features-to-firefox

Last checked 8 Nov 2026. This guide is general information, not medical advice.