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About UltraBlock

UltraBlock is a browser extension for Chrome, Edge and FireFox. It is an all-in-one adblock and privacy protection extension that blocks ads, invisible trackers and third-party cookies. It makes websites load super-fast and prevents third-parties from tracking you online.

When you visit a website, you don’t think about everything that is loaded into your browser. You read the text, look at the images and click on a hyperlink in the navigation to the next page. While you are browsing a website many things are loaded in the background. Websites use analytics software like Google Analytics or Matomo, load functionally from social media platforms or run ads. An average website loads five different external services.

Most of these external services are not relevant for you. They are unnecessary, slow down your browser and possibly track and profile you without you knowing it. External services can detect your exact location, device, browser, behavior and in many cases track you while you visit different websites. That’s why we created UltraBlock.

Hostnames from ads and trackers

How it works

When you visit a webpage, for example, your browser starts by downloading the HTML code of that page. It will start to translate the HTML code into a visual page that you can see in your browser, we call this process rendering.

A part of the rendering process is loading all the individual elements like stylesheets, images and scripts. If these elements are hosted on a different domain, then we know it is an external element, or as we call it, an external service. By using our ad and trackers database we know what these external services are used for and blocks the once that are unnecessary.

Ad and tracker database

UltraBlock manually identified 25.286 hostnames and created a publicly available database out of it. It contains popular third-party services including their name, description, logo and hostnames that are owned and operated by the same owner. UltraBlock uses this database to identify and block unnecessary ads and trackers making your browser faster and protecting your privacy.

At the top right of UltraBlock there is an on and off toggle. When you turn off UltraBlock you can exactly what third-party services are loaded in the background of a website. Additionally, you can see in what countries they store your data.

Ad and tracker database
Privacy settings

Privacy protection

External services can detect your exact location, device and browser. Because in many cases they are installed on many websites that you visit they can easily track and profile you. They keep track of what kinds of websites you visit, how long you stay there and what parts of a page you read and interact with. Most of these services can automatically be blocked by UltraBlock.

UltraBlock has different privacy protection features that prevent unknown services from tracking you. UltraBlock automatically deletes third-party cookies, clears the cache ow your browser so images can’t be tracked and can even randomize your user-agent.


We always keep on improving our service. When you installed UltraBlock your browser wil automatically update the extension to the newest version. In this changelog you can see what changes we made to the extension over time. Feel free to contact us if you have any questions or feature request.

Version Date Changes
1.6.4 2022-12-02
  • Increased efficiency by ignoring new tabs until they contain a real website.
  • Validate settings to prevent loss of settings after updating extension.
  • Replaced custom URI class with default Mozilla functions for more stability.
1.6.3 2022-11-13
  • Automatically update tracker and useragent database every 3 hours.
  • Improved retrieval of blocked hostnames using specific timestamp.
  • Implemented try statements around code used to fetch resources.
  • Restructured project files and folders.
1.6.2 2022-09-10
  • Fixed issue with retrieving limited matched rules from declarativeNetRequest.
  • Automatically remove all known ads from page.
1.6.1 2022-09-06
  • Removed onRuleMatchedDebug because it can not be used in production.
1.6.0 2022-09-04
  • Upgraded UltraBlock extension to Manifest v3.
  • Increased number of detected types used by serviced from 7 to 15.
  • Improved performance by optimizing logic to detect services.
  • Updated badge colors so number of services is visible in dark theme.
  • Removed feature to disable UltraBlock only for a specific website.
  • Removed feature to turn automatically blocking on and off.
  • Removed the feature to automatically overwrite the referer with UltraBlock.
  • Rotating user-agent is final and will only change on restart browser.
  • Updated the settings screen on the website and the extension.
  • Replaced disallowing of services with hostnames.
  • Replaced XMLHttpRequest throughout whole extension by fetch.
  • Added notification to reload page after enabling or disabling services.
  • Updated country flags for hostnames that are loaded in the background.
  • Popup with results will only look up country flags for IPv4 addresses.
  • Created four types of badges for: blocked, prevented, escaped and loaded.
1.5.1 2022-05-21
  • Moved from SVN (CodeBaseHQ) to GIT (Github).
  • Improved the logic behind the rotating user-agent feature (remains beta).
  • Improved error handling with API communication.
  • Optimized flushing process in case data sharing with Ultrablock is enabled.
1.5.0 2022-01-06
  • Complete re-design of user interface with dark and light theme.
  • Added high resolution icons for 100 most popular trackers.
  • For each service that is loaded we show the country where your data is stored.
  • Easily enabled and disable UltraBlock for a specific website or in general.
  • Easily block and unblock third party services from the main navigation.
  • Added traffic estimations based upon extension usage to the extension.
1.4.8 2021-05-27
  • Added support for Chrome, FireFox and Edge (all Chromium browser).
  • Added system information to metadata when flushing data.
1.4.7 2021-03-14
  • Translated UltraBlock to English, Spanish, Dutch, German and French.
  • Rewrote all classes and IDs (CSS, HTML, Javascript) from - to _ types.
1.4.6 2019-09-02
  • Updated title and description in manifest file to be found better.
  • Added new privacy policy on website for Chrome web store.
1.4.5 2019-06-01
  • Users can share the pages they visit and results with us without sending PII.
  • Applied color schema for console (only visible in developer mode).
1.4.4 2018-08-30
  • Upgraded JavaScript code to ES6 (using let instead of var).
  • Updated uri class (getDomain) to work with new gTLD domains as well.
  • Added selecting TabId based on hostname for detection of frames.
  • UltraBlock is now also mapping all the frames that are loaded.
  • Resolved issues with Facebook, Bing and LinkedIn and address bar.
  • Fixed 'user-agent tab bug' so each session has the same user-agent.
  • Popup now show correctly who loaded who.
1.4.3 2018-05-14
  • UltraBlock tracker database protection and blacklisting of IP addresses.
  • Prevented services show now also what initialized them.
  • Moved disable UltraBlock bar at bottom of pop-up.
  • New manifest file with additional privacy settings.
1.4.2 2017-12-20
  • Fixed issue with database protection on the API.
  • Fixed bug with returning user agents and empty list.
1.4.1 2017-08-06
  • More efficient counting of trackers.
  • Added frames and if they are visible.
  • Added initiator to hostnames.
  • Showing initiators of each service.
  • Counting of elements is now based on URLs loaded.
  • The xmlhttprequest and ping types are not both called XHR.
1.4.0 2017-07-03
  • Added domain and hostname aliases.
  • Fixed some lookup bugs in the popup.
1.3.x 2017-04-30
  • Added on uninstall event so users can give us feedback.
  • A service can now have multiple domains names and subdomains.
  • Added a description in case the extension does not detect any services.
  • Memory optimization by making less use of stringify and parse functions.
Versions before 1.3 where private versions.