Free Anti-AdBlock Script vs Paid: What Publishers Actually Need

There are two distinct things people mean when they search for a free anti-adblock script. The first is a self-hosted, open-source script you drop into your site at zero cost. The second is a managed service with a free tier, meaning the vendor handles maintenance, updates, and detection logic while you stay on a no-cost plan up to some monthly limit. Both are genuinely free. But they are not the same product, and conflating them is how publishers end up with a broken detector six months after launch

Self-hosted scripts cost nothing upfront and require everything afterward. You own the code, which means you own every filter list update, every browser regression, and every MV3-era edge case that breaks your detection logic. Managed free tiers shift that maintenance burden to the vendor in exchange for a usage cap. For most small publishers, that trade is obviously worth making, but it helps to see the full picture before deciding

The actual cost of adblock blindness is not abstract. Publishers typically lose 18 to 32 percent of ad impressions to adblock users. If you run a mid-traffic blog and you have no detection layer at all, you are flying completely blind on what is likely your largest unmonitored revenue drain. The right free option is the one that keeps working long enough to actually help you, not the one that looks easiest to set up on day one

BlockAdblock was the dominant open-source solution for years. It works by injecting a bait element into the DOM and checking whether an ad blocker hides or removes it. The logic is simple, which is both its strength and its weakness. Simple bait elements are easy for filter list maintainers to target. uBlock Origin's cosmetic filters have included BlockAdblock detection rules for a long time, meaning a meaningful share of adblock users will silently pass your detector even when they are blocking ads. The project has seen sporadic maintenance, and MV3-based extensions like uBlock Origin Lite require detection approaches that DOM bait alone cannot cover

GitHub has dozens of adblock detection snippets in varying states of repair. The best ones combine a DOM bait check with a fetch-based probe, requesting a URL that looks like an ad network endpoint and checking whether it resolves. These work better than single-vector scripts, but they still rely on filter lists not having caught up yet. The moment a major filter list adds your bait URL or bait class name, your detection rate drops to near zero and you will not know until you notice your stats look wrong

IAB DetectAdBlock is the standard maintained by the Interactive Advertising Bureau. It is more credible than random GitHub scripts and gets more consistent maintenance attention. But it is still fundamentally a single-method detector, and the IAB's public bait assets are well-known to filter list authors. It gives you a baseline, not production-grade detection. For a small site that wants something that mostly works, it is a reasonable starting point, with the expectation that you will need to revisit it every time a major browser or extension update lands

Every adblock detection script is in an ongoing arms race with filter list maintainers. uBlock Origin's filter lists are updated multiple times per week. When a new bait pattern is identified, it gets added to the list, and every user who has that list active will slip through your detection. If your script has not been updated to rotate its bait assets or change its detection vectors, your reported detection rate silently falls, and you have no way of knowing without A/B testing against a known good baseline

The MV3 transition has made this worse. Manifest V3 extensions like uBlock Origin Lite use declarativeNetRequest rules instead of dynamic JavaScript injection, which means some classic detection techniques that relied on observing the extension's behavior no longer apply cleanly. Scripts written before MV3 became mainstream often miss Lite users entirely. Brave Shields, which is enabled by default for all Brave browser users, adds another detection surface that generic scripts rarely handle correctly

The practical result is that a self-hosted adblock detection script that showed 20 percent detection rates when you installed it may be showing 8 to 12 percent a year later, not because fewer users are blocking ads, but because the script is not catching them anymore. Without multi-vector detection that is actively maintained against current filter lists, you are measuring a shrinking slice of your actual adblock population

The structural problem is that a static script is a fixed artifact competing in an arms race where the other side updates daily. The adblock killer guide compares this DIY lifecycle against what a maintained service actually keeps up with, useful reading before you spend time maintaining your own.

AntiAdBlock Core's free tier gives you up to 10,000 adblock detections per month, permanently, not a trial, not a 14-day window. The detection engine is a continuously maintained, multi-signal system that reaches 99.7 percent precision across uBlock Origin, uBlock Origin Lite (including MV3/declarativeNetRequest), AdBlock Plus, AdGuard, Brave Shields, and Ghostery. You get one line of JavaScript in your page's head tag. The vendor handles all filter list monitoring, bait rotation, and extension compatibility, you do not touch the detection logic at all

For context on what 10,000 detections per month means in practice: this is detections, not page views. At typical adblock usage rates of 20 to 30 percent, 10,000 monthly detections corresponds to roughly 33,000 to 50,000 monthly page views before you approach the cap. Most small blogs and niche publishers sit well inside this range. The free tier is not a hobbled demo, it is a complete detection product at a scale that covers the majority of independent publishers

The setup takes under five minutes. Register at /register, add the script tag to your head, and your dashboard starts populating with detection data. The revenue loss calculator at /calculator lets you input your traffic numbers to estimate what adblock users are actually costing you. Publishers using AntiAdBlock Core see an average 38 percent revenue recovery and a 65 percent whitelist rate among detected users

The free tier is the right answer for most small publishers. Consider moving to a paid plan when one or more of the following applies: your monthly adblock detections are consistently exceeding 10,000; you want access to recovery message customization and A/B testing features that optimize your whitelist conversion rate; you need priority support with response time commitments; or you are running multiple high-traffic properties and need consolidated analytics across sites

Paid plans start at around $9 per month. The decision is straightforward once you have a few weeks of detection data from the free tier. If your recovery numbers show you are recapturing meaningful ad revenue from previously invisible adblock users, the paid plan cost is covered many times over. If you are a small publisher with under 50,000 monthly page views and detection counts stay under 10,000, the free tier may serve you indefinitely

The honest comparison: a maintained self-hosted script costs you time, initial setup, ongoing updates, regression testing after every major browser or extension release. A managed free tier costs you nothing in that category and gives you better detection. The only scenario where self-hosting wins is if you have specific data-residency requirements that prevent sending detection signals to a third-party service. For everyone else, the managed free tier is the better free option