Safari, Firefox, and Brave together represent 20-25% of your website visitors—and each one breaks your tracking in a completely different way. Safari’s ITP caps cookies to 7 days. Firefox ETP strips tracking parameters from URLs. Brave blocks your analytics scripts entirely. Standard client-side tracking cannot survive this triple threat (Cloudflare Q4 2024).

The problem isn’t just one browser. It’s the cumulative effect of three different privacy mechanisms, each requiring a different workaround with traditional tools. Here’s exactly what each browser does to your data—and the single solution that handles all three.

The Combined Impact: Quantifying Your Invisible Visitors

Most articles discuss browser privacy features individually. That misses the point. Your actual data loss is cumulative:

• Safari: 16.7% of global traffic (Cloudflare Q4 2024). Every JavaScript-set cookie expires in 7 days—or 24 hours if the user arrived with tracking parameters like gclid or fbclid.
• Firefox: 4% of global traffic (Cloudflare Q4 2024). Enhanced Tracking Protection strips tracking parameters from URLs and blocks known trackers.
• Brave: 100+ million monthly active users (Brave 2025). Shields block GA4, Meta Pixel, and most analytics scripts by default.

Combined: 20-25% of your visitors are affected by privacy features that kill or restrict standard tracking.

But wait—it gets worse on mobile. All iOS browsers, including Chrome and Firefox on iPhone, use Safari’s WebKit engine under the hood. That means Safari’s ITP restrictions affect 27% of mobile traffic regardless of which browser icon users tap (StatCounter 2024).

You may be interested in: Brave Browser Is Killing Your GA4 Data: What 100M Privacy-First Users Mean for WordPress Tracking

Browser #1: Safari ITP—The 7-Day Attribution Killer

Safari’s Intelligent Tracking Prevention doesn’t block scripts. It’s more subtle—and arguably more damaging to attribution.

What Safari ITP does:

• Blocks all third-party cookies completely
• Caps JavaScript-set first-party cookies to 7 days
• Reduces that to 24 hours if the user arrived with known tracking parameters (gclid, fbclid, etc.)
• Partitions LocalStorage so cross-site identification fails
• Deletes all site data after 30 days without interaction (CookieStatus)

The attribution problem: A customer clicks your Facebook ad on Monday, browses, then returns to purchase on day 8. Safari has already deleted the cookie that would attribute that sale to Facebook. Your ROAS looks worse than reality because Safari users lose attribution after a week.

Server-set cookies via HTTP headers bypass this restriction—but only if set from the same IP address as your server. Client-side workarounds don’t exist.

Browser #2: Firefox ETP—The Parameter Stripper

Firefox Enhanced Tracking Protection takes a different approach. Scripts can load. Cookies can set. But tracking parameters often never arrive.

What Firefox ETP does:

• Blocks known trackers using disconnect.me lists
• Strips tracking parameters like fbclid, gclid, and mc_eid from URLs
• Blocks cryptominers and fingerprinting scripts
• Partitions cookies for cross-site requests

The attribution problem: Your Google Ads campaign sends traffic with ?gclid=abc123. Firefox strips the gclid before your analytics even sees it. The visitor converts, but you can’t attribute the sale to the campaign that drove it.

Over 20% of Firefox users enable Enhanced Tracking Protection (BrowserStack). That’s 20%+ of a 4% browser share losing your campaign parameters.

Browser #3: Brave—The Script Killer

Brave doesn’t bother with subtle cookie manipulation or parameter stripping. It simply blocks your tracking scripts from loading.

What Brave Shields block:

• Google Analytics (GA4) entirely
• Meta Pixel (Facebook tracking)
• Adobe Analytics
• TikTok Pixel
• Most third-party measurement vendors

The attribution problem: GA4 never loads. Meta Pixel never fires. Your analytics shows zero visitors from Brave—but they’re there, browsing and buying. They’re just completely invisible to client-side tracking.

Brave reached 100+ million monthly active users in 2025, with 31.5% of global internet users running some form of ad blocking. This isn’t a niche concern. It’s a quarter of the internet that traditional analytics cannot see.

You may be interested in: Ad Blockers Are Stripping Your UTM Parameters Before You See Them

Why Traditional Solutions Fail the Triple Threat

Each browser requires a different workaround with traditional tools:

For Safari ITP: You need server-set cookies via HTTP headers from a first-party domain. GTM server-side can do this—if you have the technical expertise to configure it.

For Firefox ETP: You need coded UTM parameters that don’t match known tracking patterns. Custom solutions exist, but require ongoing maintenance as filter lists update.

For Brave: You need server-side event delivery that bypasses the browser entirely. Client-side workarounds don’t exist—if Brave blocks the script, it’s blocked.

Most WordPress store owners don’t have the resources to implement three separate workarounds across three different systems. They just accept the data loss.

Server-Side Tracking: One Solution for All Three

Server-side tracking from a first-party domain solves all three problems simultaneously:

Safari bypass: Cookies set via HTTP headers from your own server aren’t subject to ITP’s 7-day JavaScript cookie limit. First-party server-set cookies maintain full attribution windows.

Firefox bypass: Parameters captured server-side before the browser processes them survive ETP stripping. The server sees the original URL including tracking parameters.

Brave bypass: Server-side requests don’t run in the browser. Brave cannot block what never executes in the client. Events fire from your server, not from blocked JavaScript.

The key: first-party deployment. Server-side tracking only works if it runs from your own domain (e.g., data.yourstore.com). Third-party server domains still get blocked or restricted. True first-party architecture is non-negotiable.

Implementing First-Party Server-Side Tracking

For WordPress sites, Transmute Engine™ provides the complete first-party server-side solution without GTM complexity. It’s a dedicated Node.js server that runs on your subdomain—not a WordPress plugin that adds PHP load.

The architecture: inPIPE WordPress plugin captures events from WooCommerce hooks, batches them, and sends via API to your Transmute Engine server. The server formats, enhances, and routes events simultaneously to GA4, Facebook CAPI, Google Ads, and BigQuery—all from your first-party domain.

One setup handles Safari, Firefox, and Brave. No three separate workarounds. No GTM expertise required. No ongoing filter list maintenance.

Key Takeaways

• Safari (16.7% market share) caps cookies to 7 days—killing attribution for customers who don’t convert immediately
• Firefox (4% market share with 20%+ ETP adoption) strips tracking parameters—breaking campaign attribution at the source
• Brave (100M+ users) blocks scripts entirely—making visitors invisible to client-side analytics
• Combined effect: 20-25% of traffic affected by privacy features that standard tracking cannot handle
• Server-side from first-party domain bypasses all three—cookies avoid ITP, parameters survive stripping, requests bypass blocking

Stop losing a quarter of your data to privacy browsers. Learn how Transmute Engine recovers your invisible visitors.