Firefox Now Blocks Trackers for Everyone

What changed today

Firefox 69, released today, turns on Enhanced Tracking Protection for everyone who uses it. Until now it was on by default only for people who installed Firefox after early June, or who switched it on themselves.

In its standard setting, it blocks cookies from a list of known tracking companies when their code runs inside other sites' pages. It also blocks scripts that use visitors' computers to mine cryptocurrency.

Most pages look and work exactly as before. Visitors see nothing apart from a small shield in the address bar.

What changes is what some of the tags on your site can remember about the people using Firefox.

Whose cookie it is

A cookie is a small piece of information a site stores in the browser, so it can recognise that browser later. Whose cookie it is decides whether this change touches it.

A first-party cookie belongs to the site in the address bar. Universal Analytics uses one: it stores its identifier on your own domain.

A third-party cookie belongs to another company whose code runs inside your page, such as an advertising network. The same code runs on thousands of sites, so its cookie can recognise one browser across all of them.

That recognition across sites is what Firefox now blocks, for companies on its list. Your own site's cookies are untouched.

What it touches, and what it does not

• Retargeting lists that ad networks build from your visitors, which now miss many Firefox users.
• Ad conversion counts that rely on the network recognising a visitor later.
• View-through conversions, credited to ads somebody saw but never clicked.
• Demographics and interests reports in Analytics, which use an advertising cookie.
• Ordinary visit counts in Analytics, which carry on as before.

The fourth surprises people, since it sits inside Analytics. Age, gender and interest figures come partly from an advertising cookie on Google's ad domain, so Firefox visitors will drop out of those reports while still being counted as visits.

Why your own analytics mostly carries on

Universal Analytics sets its cookie from your own domain and sends each page view to Google from your page. In ordinary windows, the standard setting leaves that alone.

Two groups of Firefox users were already hard to count. Private windows have blocked many tracking scripts, including some analytics, for several years.

And people who choose the strict setting block those scripts in every window. Some will, now that the shield has drawn their attention to it.

So a small dip in Firefox visits is possible. A large drop is more likely to be broken tracking code than this change.

Advertising is where it shows

A retargeting list is a list of browsers an ad network has seen on your site and can recognise elsewhere. With the network's cookie blocked, Firefox visitors cannot be found again on other sites.

So the list grows more slowly and leans further toward Chrome users. Conversions that depend on the network recognising the same browser later go missing for Firefox in the same way.

Some platforms also keep a click identifier in a first-party cookie on your domain, which this change does not block, so how much each one loses will vary.

Safari has restricted cookies like these for some time. Chrome, which most visitors use, does not block them by default.

A worked example

A hot tub and sauna retailer with one showroom has customers who often spend weeks deciding, and stays in front of them with retargeting ads shown across other websites.

Its Analytics showed most visitors on phones, but a noticeable share of evening desktop visitors, the ones comparing models and reading specifications, used Firefox.

As Firefox updates over the coming days, those visitors stop joining the retargeting lists that depend on the networks' own cookies, and some quote requests they send later will not be credited to any ad.

Nothing about the customers will change. The showroom will still see them; the ad dashboards will see fewer of them.

The owner annotated today's date in Analytics, so a shift in this month's ad figures has an explanation on the chart, and added a field to the quote form for how people first heard of the business.

The campaigns will be judged on quote requests and showroom visits counted in-house, with the platforms' figures as a second opinion.

See what Firefox blocks on your site

Open your own site in an up-to-date Firefox and look at the left of the address bar. If anything was blocked, a shield appears there.

Click it, and Firefox shows what it blocked on that page.

The list is often a surprise: tags added for campaigns that ended years ago, or code that arrived with a plugin, setting cookies for companies you no longer deal with.

Remove the ones you no longer use. A tag nobody needs is a privacy question and a speed cost, with nothing on the other side.

Read Firefox separately for a while

In Analytics, the browser report under Audience, then Technology, shows what share of visits and goals comes from Firefox. Note it now.

For many local businesses Firefox is a small slice, and the effect will be small. Where it is larger, compare the next two months with the last two, browser by browser.

A dip confined to the ad platforms' Firefox figures is this change. A dip in every browser is something else.

What not to do

Do not try to disguise third-party tracking as first-party. Safari has already begun limiting first-party cookies that behave like tracking, and the workaround sits badly with the privacy policy on your own site.

Do not cut a campaign because its Firefox conversions fell. Compare against the enquiries you counted yourself first.

The counter-case

For many small businesses this changes very little.

A business that runs no retargeting or conversion-tracked ads loses part of a demographics report few owners act on.

One whose customers arrive mostly on phones may barely notice, since Firefox is used far more on desktops and laptops.

Where budgets depend on ad platform figures, though, read the next few months knowing Firefox users are partly missing from them, and count enquiries yourself.

This week

1. Open your site in Firefox and click the shield.
2. List every tag it shows as blocked.
3. Remove tags you no longer use.
4. Annotate today's date in Analytics.
5. Note Firefox's share of visits and goals.
6. Count enquiries yourself alongside the ad reports.
7. Compare by browser after two months.

Step six is the one that makes every browser change survivable. Ad platforms see what browsers let them see; an enquiry you logged yourself is counted whatever any browser decides.

Safari's version of the same idea is covered in Safari tightens its cookie rules again.

Frequently asked questions

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.