Firefox 87 Introduces 'SmartBlock' Private Browsing Feature to Fix Websites Broken By Tracking Protections

Mozilla has released Firefox 87 for Macs, Windows, and Linux machines, introducing a new intelligent tracker blocking mechanism called SmartBlock.

mozilla firefox banner
Since 2015, Firefox has included a built-in Content Blocking feature that automatically blocks third-party scripts, images, and other content from being loaded from cross-site tracking companies in Private Browsing windows and Strict Tracking Protection Mode.

Mozilla recognizes that the feature sometimes blocks legitimate elements of websites which can cause them to malfunction. SmartBlock aims to provide a solution to this problem without compromising user privacy. From the company's blog:

In building these extra-strong privacy protections in Private Browsing windows and Strict Mode, we have been confronted with a fundamental problem: introducing a policy that outright blocks trackers on the web inevitably risks blocking components that are essential for some websites to function properly. This can result in images not appearing, features not working, poor performance, or even the entire page not loading at all.

To reduce this breakage, Firefox 87 is now introducing a new privacy feature we are calling SmartBlock. SmartBlock intelligently fixes up web pages that are broken by our tracking protections, without compromising user privacy.

Mozilla says SmartBlock works by providing local stand-ins for blocked third-party tracking scripts that behave "just enough" like the original ones to make sure that the website works properly.

The stand-ins come built-in to Firefox, so no third-party content from the trackers is loaded by the browser, meaning they can't track users this way. According to the developers, SmartBlock will silently stand in for several common scripts classified as trackers on the Disconnect Tracking Protection List, and should provide a noticeable performance improvement while browsing.

The previous version of the browser introduced Total Cookie Protection, which is designed to stop cookies from tracking users across the web. Firefox 87, the latest update, is available now from the Mozilla website.

Popular Stories

Apple Wallet ID Illinois

Apple Plans to Expand iPhone Driver's Licenses to These 7 U.S. States

Wednesday December 24, 2025 8:40 am PST by
In select U.S. states, residents can add their driver's license or state ID to the Apple Wallet app on the iPhone and Apple Watch, and then use it to display proof of identity or age at select airports and businesses, and in select apps. The feature is currently available in 13 U.S. states and Puerto Rico, and it is expected to launch in at least seven more in the future. To set up the...
maxresdefault

Where's the New Apple TV?

Monday December 22, 2025 11:30 am PST by
Apple hasn't updated the Apple TV 4K since 2022, and 2025 was supposed to be the year that we got a refresh. There were rumors suggesting Apple would release the new Apple TV before the end of 2025, but it looks like that's not going to happen now. Subscribe to the MacRumors YouTube channel for more videos. Bloomberg's Mark Gurman said several times across 2024 and 2025 that Apple would...
iPhone Top Left Hole Punch Face ID Feature Purple

iPhone 18 Pro Launching Next Year With These 12 New Features

Tuesday December 23, 2025 8:36 am PST by
While the iPhone 18 Pro and iPhone 18 Pro Max are not expected to launch for another nine months, there are already plenty of rumors about the devices. Below, we have recapped 12 features rumored for the iPhone 18 Pro models. The same overall design is expected, with 6.3-inch and 6.9-inch display sizes, and a "plateau" housing three rear cameras Under-screen Face ID Front camera in...
iOS 26

iOS 26.2 Adds These 8 New Features to Your iPhone

Monday December 22, 2025 8:47 am PST by
Earlier this month, Apple released iOS 26.2, following more than a month of beta testing. It is a big update, with many new features and changes for iPhones. iOS 26.2 adds a Liquid Glass slider for the Lock Screen's clock, offline lyrics in Apple Music, and more. Below, we have highlighted a total of eight new features. Liquid Glass Slider on Lock Screen A new slider in the Lock...
iOS 26

iOS 26.3 Brings AirPods-Like Pairing to Third-Party Devices in EU Under DMA

Monday December 22, 2025 3:20 pm PST by
The European Commission today praised the interoperability changes that Apple is introducing in iOS 26.3, once again crediting the Digital Markets Act (DMA) with bringing "new opportunities" to European users and developers. The Digital Markets Act requires Apple to provide third-party accessories with the same capabilities and access to device features that Apple's own products get. In iOS...
iPhone Fold Vertical Feature

Why Apple's Foldable iPhone May Be Smaller Than Expected

Tuesday December 23, 2025 5:21 am PST by
Apple's first foldable iPhone, rumored for release next year, may turn out to be smaller than most people imagine, if a recent report is anything to go by. According to The Information, the outer display on the book-style device will measure just 5.3 inches – that's smaller than the 5.4-inch screen on the ‌iPhone‌ mini, a line Apple discontinued in 2022 due to poor sales. The report has led ...
iPhone Chips

Apple Clings to Samsung as RAM Prices Soar

Monday December 22, 2025 6:17 am PST by
Apple is significantly increasing its reliance on Samsung for iPhone memory as component prices surge, according to The Korea Economic Daily. Apple is said to be expanding the share of iPhone memory it sources from Samsung due to rapidly rising memory prices. The shift is expected to result in Samsung supplying roughly 60% to 70% of the low-power DRAM used in the iPhone 17, compared with a...
maxresdefault

10 Mac Apps Worth Trying in 2026

Wednesday December 24, 2025 9:27 am PST by
2026 is almost upon us, and a new year is a good time to try out some new apps. We've rounded up 10 excellent Mac apps that are worth checking out. Subscribe to the MacRumors YouTube channel for more videos. Alt-Tab (Free) - Alt-Tab brings a Windows-style alt + tab thumbnail preview option to the Mac. You can see a full window preview of open apps and app windows. One Thing (Free) -...
Foldable iPhone 2023 Feature Iridescent Search

Samsung Developing 'Wide Fold' With iPhone Fold-Like Design Ahead of Apple's 2026 Launch

Tuesday December 23, 2025 11:55 am PST by
Samsung is working on a new foldable smartphone that's wider and shorter than the models that it's released before, according to Korean news site ETNews. The "Wide Fold" will compete with Apple's iPhone Fold that's set to launch in September 2026. Samsung's existing Galaxy Z Fold7 display is 6.5 inches when closed, and 8 inches when open, with a 21:9 aspect ratio when folded and a 20:18...

Top Rated Comments

Nozuka Avatar
62 months ago
I love their Container feature. You can create seperate "Cookie containers" for websites like Facebook, Youtube, etc.
That way you will keep your settings on these websites, but when you visit other websites, they can't abuse these cookies for tracking you, since they are not available there. Or a seperate container for e-banking.

It also allows you to have several containers for the same website, so you can use more than one user on the same website. Very convenient if you have a personal and a business Office 365 account, for example.

Requires the extension from firefox: "Multi-account Containers" to make full use of it.
Score: 32 Votes (Like | Disagree)
wanha Avatar
62 months ago
Never been much of a Firefox user, but I applaud Firefox for their actions on privacy.
Score: 25 Votes (Like | Disagree)
adrianlondon Avatar
62 months ago

Never been much of a Firefox user, but I applaud Firefox for their actions on privacy.
I'm surprised that Firefox actually runs faster on my MBA (Big Sur latest beta) than Safari, although I think that's due to the amount of stuff it natively blocks, along with uBlock Origin, rather than any rendering advantages.

Two main reasons I prefer Firefox. (1) cookie control especially with Containers and (2) the way going to previous pages while reading forums doesn't reload and send pages pack to the top. Oh, and (3) uBlock Origin.
Score: 21 Votes (Like | Disagree)
Bandaman Avatar
62 months ago
Dunno what's going on with Firefox lately, but it's ridiculously fast on my Mac.
Score: 13 Votes (Like | Disagree)
MJaP Avatar
62 months ago
I always use Firefox on my Windows PCs, I've found it fast and secure. Best alternative to Safari in my opinion.
Score: 9 Votes (Like | Disagree)
Bandaman Avatar
62 months ago

Faster than Safari?
Yes. Much. And if you go into about:config and up the process count from 8 to say ... 100 ... it's comically faster. This is easily faster than Chrome, Edge, Safari, and Brave. It's also incredibly smooth and stable. Just the whole feel of this version of Firefox is really great. This will be my main browser again for a while and I've been on brave for quite some time. Also, the ad blocking by default on iOS is really great, even blocks stuff Brave seems to miss. I don't see most ads on websites with Firefox when I set it to strict mode.

Another very important point ... I can open a million tabs in Firefox and nothing slows down. Like ... at all ... and all the websites are responsive. I'm honestly impressed. Hopefully these great strides in the Firefox experience keeps them from disappearing. We need more non-Chromium browsers competing with Google. Sucks that Google basically owns 90% of the browser use market with either Chrome or a Chromium-based browser ... so much that even Microsoft caved in. I'm glad to support Mozilla for not being like everyone else.
Score: 6 Votes (Like | Disagree)