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Shopify CAPI Problems: 3 Major Issues and How to Fix Them

Written by Noah King | Jul 1, 2025 7:26:56 PM

When merchants run ads on Facebook or Instagram, accurate data is important. Meta uses that data to decide who sees ads, when they see them, and how much is paid for each click or conversion.

Shopify offers a free setup for Meta's Conversions API (CAPI), but it has limitations. Many brands rely on it without realizing what's missing. Shopify's default client-side tracking misses 20-30% of purchases due to browser restrictions.

Meta's Conversions API (CAPI) sends event data directly from your store's server to Meta's systems. Unlike browser-based tracking (the Meta Pixel), CAPI works even when browsers block cookies or users have ad blockers installed. In fact, 32.2% of U.S. internet users employ ad blockers, severely limiting pixel-based tracking effectiveness.

Why CAPI Matters for Shopify Brands

Meta's Conversions API (CAPI) sends event data directly from your store's server to Meta's systems. Unlike browser-based tracking (the Meta Pixel), CAPI works even when browsers block cookies or users have ad blockers installed.

When your store uses both CAPI and the Meta Pixel together, Meta receives a more complete picture of how people interact with your store. This helps Meta match events to users more accurately. CAPI captures 92% of conversions compared to only 72% for pixel-only setups.

If your tracking setup misses events or counts them twice, Meta's optimization becomes less effective. Brands implementing proper CAPI solutions saw 2.8x reduction in cost-per-purchase. This often leads to higher ad costs or fewer conversions from your budget.

If your tracking setup misses events or counts them twice, Meta's optimization becomes less effective. This often leads to higher ad costs or fewer conversions from your budget.

The 3 Major CAPI Issues in Shopify

1. Inflated attribution: every order is treated as a single “Purchase” event

Shopify’s free CAPI fires the same Purchase event for all transactions that flow through your store, whether they came from paid ads or not.

  • One-off vs. subscription renewals: recurring subscription charges are re-sent to Meta as brand-new purchases, overstating ROAS.
  • Non-ad channels: partner fulfilments, Amazon marketplace orders, or customer-service re-orders all trigger Purchase events despite never touching your ads.
  • Result: ad platforms “claim” revenue they didn’t drive, skewing reporting and pushing the algorithm to optimise for the wrong signals.

2. Lost click-IDs from multi-session checkouts (-20 % Facebook, -10 % Google capture)

Shoppers rarely convert in one sitting. A common path looks like:

  • Click a Facebook ad on Monday → browse
  • Return via direct URL on Wednesday → add to cart
  • Come back to checkout on Friday → purchase

Shopify’s native integration fails to carry the original fbclid/gclid across sessions, so Friday’s server-side Purchase arrives with no click-ID. Testing shows ≈20 % of Facebook and 10 % of Google click-IDs are lost, depriving the algorithms of the data they need to optimize and retarget.

3. “Just a relay” limits advanced media buying

The stock connection simply mirrors pixel hits to the server; it can’t enrich or segment data. Advanced buyers need:

  • Privacy filters: Many privacy tools and email clients automatically block tracking from known ad-tech domains
  • Lower match quality: When events come from Shopify domains instead of your own domain, Meta has a harder time connecting those events to specific users
  • Cross-domain limitations: Moving between your custom storefront domain and Shopify's domains can break tracking continuity

A custom first-party CAPI can stream this richer data, unlocking smarter look-alikes, tighter bid strategies, and double-digit revenue lifts.

Fixing the Free Shopify CAPI Shortcomings

Capturing Missing Events

To track events that Shopify's CAPI misses, you can use Google Tag Manager (GTM) to create a more complete tracking setup.

GTM lets you define custom events and send them to both Meta Pixel and CAPI. Here's how to approach this:

  1. Set up server-side GTM to handle both browser and server events
  2. Create triggers for important customer actions like product views and cart additions
  3. Configure these events to send through both Meta Pixel and CAPI

This approach captures more of the customer journey, giving Meta's algorithm better data to work with.

Many Shopify merchants find that tracking add-to-cart events alone can significantly improve their campaign performance, as Meta can optimize for actions earlier in the funnel.

Aligning Attribution and Reducing Mismatches

To reduce data inconsistencies between Shopify and Meta, you can take several practical steps:

  • Match attribution windows: In Meta Ads Manager, set your attribution window to match how you measure success in Shopify
  • Use consistent event names: Make sure events have the same names and parameters across both tracking methods
  • Implement deduplication: Pass the same event ID to both Pixel and CAPI versions of each event

Proper deduplication is especially important. When Meta receives the same event ID from both sources, it counts that event only once. This creates cleaner data for optimization.

For example, when someone makes a purchase, both your browser tracking and server tracking might send that event to Meta. With the same event ID attached to both, Meta knows it's the same purchase.

Using First-Party Domains for Tracking

To improve event delivery and match quality, you can move server-side tracking to your own domain instead of using Shopify's domains.

This involves:

  1. Setting up a subdomain on your main domain (like track.yourbrand.com)
  2. Configuring this subdomain to handle server-side tracking
  3. Updating your CAPI implementation to use this domain

Using your own domain helps tracking work even when privacy tools might block third-party domains. It also improves Meta's ability to match events to the right users.

Several Shopify apps and services now offer first-party domain setup for CAPI, making this process more accessible than in the past.

FAQs About Improving Shopify CAPI

How do I know if my CAPI setup is working correctly?

Check the Events Manager in your Meta Business account. Look for events coming from both your Meta Pixel (browser) and CAPI (server). If you see similar numbers from both sources with minimal discrepancies, your setup is likely working well. Meta also provides a "Setup" tab that shows the health of your connection.

Can I use multiple tracking solutions without creating duplicate data?

Yes, but it requires careful configuration. When using multiple tools that send data to Meta, use consistent event IDs across all systems. This allows Meta to recognize and count each event only once, even if it receives the event from multiple sources.

Does fixing CAPI issues improve ad performance immediately?

Improvements typically happen gradually. After fixing CAPI issues, Meta's system needs time to collect new data and learn from it. Most merchants see optimization improvements within 1-2 weeks as Meta's algorithm adapts to the more complete data it's receiving.

How do server-side events work with iOS privacy changes?

Server-side events (CAPI) can still send data even when users opt out of tracking on iOS devices. However, without browser data, the events contain less identifying information. This is why using both tracking methods together provides the best results – each method helps fill gaps the other might have.

Moving Toward Better Shopify Performance

Accurate tracking forms the foundation of understanding how your paid traffic performs. When your event data from Shopify is complete, properly deduplicated, and delivered reliably, Meta's algorithm can learn more effectively.

Each part of the tracking process affects how clearly Meta sees the customer journey. Fixing gaps in data collection helps remove uncertainty from your attribution and reporting.

Better data leads to more efficient ad spend. When Meta's system knows which actions truly lead to purchases, it can find more customers likely to convert. This often results in lower cost per acquisition and higher return on ad spend.

For Shopify merchants looking to maximize their marketing budget, addressing these CAPI limitations is often a quick win with lasting benefits.

To learn how this applies to your brand, book a demo to explore how Platter can optimize your Shopify storefront. The Platter team specializes in creating high-converting Shopify stores with proper tracking setups that help you get the most from your ad spend.