What the Conversions API Is
The Conversions API (CAPI) is Meta's way of receiving conversion events from a server instead of only from the visitor's browser. The classic Meta pixel is a piece of JavaScript that fires in the browser, so anything that stops the script, such as an ad blocker, a browser privacy feature or a closed tab, stops the event. CAPI sends the same event from your server (or a tool's server) straight to Meta.
Why CAPI Matters After iOS 14
Since iOS 14.5 and the wider squeeze on browser tracking, the pixel alone misses a meaningful share of conversions. Meta's algorithm optimizes toward the conversions it can see, so missing events make targeting worse and results look worse than they are. CAPI recovers events the browser misses and lets you send richer, hashed customer information that helps Meta match conversions to people. Our guide to Facebook ads tracking after iOS 14 covers the full picture.
CAPI doesn't override privacy choices or bring back everything that was lost. It improves the quality and completeness of the data you're allowed to send.
Pixel vs Conversions API
| Meta pixel | Conversions API | |
|---|---|---|
| Where it runs | Visitor's browser | Your server or a tool's server |
| Blocked by ad blockers | Often | No |
| Offline / CRM / phone events | No | Yes |
| Builds website audiences | Yes | Supports, alongside the pixel |
| Setup effort | Low | Low to high, depending on method |
| Recommended | Use both together, with deduplication | |
Deduplication: Don't Count Sales Twice
If you run the pixel and CAPI together, the same purchase arrives twice. Meta deduplicates when both events carry the same event_name and a matching event_id. Generate one ID per event (for example, the order ID) and send it with both. If your purchases suddenly double in Ads Manager after setting up CAPI, deduplication is the first thing to check.
Event Match Quality: Send Better Data
Each server event can include customer information parameters that Meta uses to match it to a person. Personal details must be normalized and hashed with SHA-256 before sending, and only sent where you have the right to do so.
| Parameter | What it is | Hashed? |
|---|---|---|
em | Email address | Yes |
ph | Phone number | Yes |
fn / ln | First and last name | Yes |
external_id | Your customer ID | Recommended |
fbp | Browser ID from the _fbp cookie | No |
fbc | Click ID from the fbclid parameter | No |
client_ip_address, client_user_agent | Visitor's IP and browser | No |
Meta scores how well your events match in Event Match Quality, shown in Events Manager. Passing the click ID (fbc) and a hashed email on purchase and lead events usually makes the biggest difference.
Ways to Set Up the Conversions API
| Method | Effort | Good for |
|---|---|---|
| Platform integration (Shopify, WooCommerce plugins, funnel builders) | Low | Stores and funnels on supported platforms |
| Meta's Conversions API Gateway | Medium | Advertisers who want a Meta-managed server setup |
| Server-side Google Tag Manager | Medium to high | Teams already using GTM with technical help |
| Tracking tool with conversion syncing (e.g. ClickMagick) | Low | Advertisers on several ad platforms who want one setup |
| Direct API integration | High | Custom apps with developer resources |
Setup effort by method (lower is easier)
Beyond Meta: Conversion APIs Everywhere
Meta isn't alone. Google Ads, TikTok, LinkedIn and others all accept server-side or offline conversions in their own formats. If you advertise on several platforms, setting up each one separately gets tedious. That's where tools that sync conversions to many platforms at once save time. ClickMagick's Audience Optimization, for example, sends conversions to Meta, Google, Microsoft, TikTok, LinkedIn, X and ChatGPT Ads on every plan.
CAPI Checklist
- Send purchases and leads at minimum; add other events if your campaigns optimize for them.
- Run the pixel and CAPI together, with matching
event_idvalues. - Pass
fbc,fbpand hashed email or phone where you lawfully can. - Check Events Manager for deduplication and Event Match Quality.
- Compare Meta-reported purchases against your real orders monthly.
Set up ClickMagick's version step by step in our ClickMagick tutorial, read the wider attribution guide, or browse more on the Click Tracking Guide homepage.