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

iPhone 17 Pro Dark Blue and Orange

iPhone 17 Release Date, Pre-Orders, and What to Expect

Thursday August 28, 2025 4:08 am PDT by
An iPhone 17 announcement is a dead cert for September 2025 – Apple has already sent out invites for an "Awe dropping" event on Tuesday, September 9 at the Apple Park campus in Cupertino, California. The timing follows Apple's trend of introducing new iPhone models annually in the fall. At the event, Apple is expected to unveil its new-generation iPhone 17, an all-new ultra-thin iPhone 17...
iPhone 17 Pro Iridescent Feature 2

iPhone 17 Pro Clear Case Leak Reveals Three Key Changes

Sunday August 31, 2025 1:26 pm PDT by
Apple is expected to unveil the iPhone 17 series on Tuesday, September 9, and last-minute rumors about the devices continue to surface. The latest info comes from a leaker known as Majin Bu, who has shared alleged images of Apple's Clear Case for the iPhone 17 Pro and Pro Max, or at least replicas. Image Credit: @MajinBuOfficial The images show three alleged changes compared to Apple's iP...
iphone 16 pro ghost hand

iPhone 17 Pro: 5 Reasons Not to Upgrade This Year

Monday September 1, 2025 4:35 am PDT by
Apple will launch its new iPhone 17 series this month, and the iPhone 17 Pro models are expected to get a new design for the rear casing and the camera area. But more significant changes to the lineup are not expected until next year, when the iPhone 18 models arrive. If you're thinking of trading in your iPhone for this year's latest, consider the following features rumored to be coming to...
xiaomi apple ad india

Apple and Samsung Push Back Against Xiaomi's Bold India Ads

Friday August 29, 2025 4:54 am PDT by
Apple and Samsung have reportedly issued cease-and-desist notices to Xiaomi in India for an ad campaign that directly compares the rivals' devices to Xiaomi's products. The two companies have threatened the Chinese vendor with legal action, calling the ads "disparaging." Ads have appeared in local print media and on social media that take pot shots at the competitors' premium offerings. One...
iOS 18 on iPhone Arrow Down

Apple Preparing iOS 18.7 for iPhones as iOS 26 Release Date Nears

Sunday August 31, 2025 4:35 pm PDT by
Apple is preparing to release iOS 18.7 for compatible iPhone models, according to evidence of the update in the MacRumors visitor logs. We expect iOS 18.7 to be released in September, alongside iOS 26. The update will likely include fixes for security vulnerabilities, but little else. iOS 18.7 will be one of the final updates ever released for the iPhone XS, iPhone XS Max, and iPhone XR,...

Top Rated Comments

Nozuka Avatar
58 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
58 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
58 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
58 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
58 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
58 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)