About isblocked.fyi
A lookup and monitoring tool for the other side of the adblocker market.
isblocked.fyi is a union index of major adblocker filter lists: uBlock Origin, Brave, AdGuard, AdBlock Plus, Ghostery, Firefox (ETP), Microsoft Edge (TP), DuckDuckGo, and Safari ATFP. We aggregate 31 lists and map each one to the blockers that ship it by default or as an optional add-on.
It is the only tool of this kind that combines a searchable union index with built-in domain monitoring in one product. Other resources may cover individual lists or one-off lookups; none offer daily search plus alerts when list membership changes.
This is not an adblocker. We do not block anything. We index what blockers block, so you can look up a domain and see where it appears.
Think of it as infrastructure for the tracking and analytics side of the market: the people who need to know when their domains get flagged.
If your tracking or analytics domain lands on EasyPrivacy, AdGuard Tracking Protection, or similar lists, real users with default adblockers never load your scripts. No pixel fires. No session replay. No attribution data.
Revenue reporting drops. Campaign attribution breaks. Product analytics go dark. And you often find out weeks later, when someone notices a gap in the data.
Blocklist exposure is a silent failure mode. isblocked.fyi makes it visible before it hits your dashboards.
Block type
Not every list entry blocks all traffic to a domain. Many tracking domains are blocked only as third-party resources (when loaded from another site), not when visited directly. Others block all traffic, scripts only, or XHR calls only.
On the search results page, hover the Block type column for details on each entry. "3rd-party only" means the domain works when you visit it directly, but scripts or pixels from that domain are blocked when embedded on other pages.
DuckDuckGo
DuckDuckGo Browser and the DDG Privacy Essentials extension block third-party requests to domains in their Tracker Radar compiled blocklist. Only domains where the default action is “block” are indexed here. All DDG blocks are third-party only by convention.
Safari Advanced Tracking and Fingerprinting Protection (ATFP)
Safari ATFP blocks third-party requests to domains that appear in both DuckDuckGo Tracker Radar and EasyPrivacy. On by default in Private Browsing only (Safari 17+). Regular tabs require opt-in: Settings → Advanced → Use advanced tracking and fingerprinting protection → All Browsing. This site shows Safari only when a domain is active on both lists. Source: WebKit blog.
Ghostery
Ghostery enables three engines by default: Ads (EasyList + uBlock filters), Tracking (EasyPrivacy + uBlock Privacy), and Annoyances (EasyList Cookie + uBlock Annoyances). All three are on out of the box. Source: ghostery-extension repo.
Firefox Enhanced Tracking Protection (ETP)
Firefox ETP Standard mode (default) blocks trackers from the Disconnect.me Level-1 list - Advertising, Analytics, and Social categories. Content trackers are blocked only in Private Windows in Standard mode.
Microsoft Edge Tracking Prevention
Edge TP Balanced mode (default) classifies and blocks trackers using Disconnect.me Tracker Protection lists. Like Firefox ETP, the source lists are the same Disconnect Advertising and Analytics categories.
Default vs optional lists
Each blocker ships with a set of lists enabled out of the box. uBlock Origin defaults to EasyList and EasyPrivacy. Brave has its own lists. AdGuard and AdBlock Plus have their own defaults.
Users can also enable optional lists (Fanboy Annoyances, regional lists, etc.). A domain blocked only by an optional list affects fewer users than one blocked by a default list.
Search results show "Blocked by default" and "Optional lists" separately so you can gauge real-world exposure.
Enter a domain (e.g. google-analytics.com) or a keyword on the homepage. Results show every matching domain across our index.
Match types tell you how the result relates to your query: exact match, parent domain, subdomain, or keyword substring.
Each row lists the filter list, category (ads, tracking, malware, etc.), block type, which blockers use that list, and when the domain was first seen. Previously listed entries show removal dates.
Search is free and requires no account. Monitoring requires sign-in.
Add a domain or regex pattern to your dashboard. We check all indexed lists daily. When your domain is added to or removed from any list, you get an email alert and/or a webhook POST (depending on your setup).
History is tracked: you can see when a domain first appeared on a list and when it was removed. Useful for correlating blocklist changes with drops in your analytics.
Open the dashboard to add a monitor.
- Analytics engineers validating data pipeline coverage
- MarTech teams managing third-party tag inventories
- Anyone running third-party tracking, analytics, or attribution infrastructure
If a blocklist change can break your measurement without anyone noticing, this tool is for you.
isblocked.fyi indexes public filter lists and maps them to known blockers. Lists are re-fetched daily; methodology and limitations are documented on this page. Wrong result? Use the contact form. We'll fix them.
Built and maintained by Mariusz Brucki. Background: mariuszbrucki.pl.