The Meta Conversions API (CAPI) sends your conversion events, purchases, leads, sign-ups, from your server straight to Meta. Used together with the Meta Pixel, it recovers conversions that browsers block and gives Meta better data to optimise your ads. Event Match Quality (EMQ) is Meta’s 0 to 10 score for how well those events can be matched to real people; the higher it is, the better Meta can learn who converts.
Why the Conversions API matters now
The browser Pixel relies on cookies and JavaScript running in the visitor’s browser. Ad blockers, browser privacy features and mobile privacy changes mean some of those events never reach Meta.
When Meta sees fewer conversions:
- your reported CPA looks higher than reality,
- the algorithm has less signal to optimise delivery, and
- ad sets struggle to exit the learning phase.
CAPI fixes the gap by sending the same events from your server, where browsers can’t block them. Meta’s own guidance is to use Pixel + CAPI together.
Pixel vs Conversions API
| Meta Pixel | Conversions API | |
|---|---|---|
| Runs in | The visitor’s browser | Your server (or a partner’s) |
| Affected by ad blockers | Yes | No |
| Can send offline / CRM events | No | Yes |
| Setup effort | Low (paste a snippet) | Low with a partner, higher if built directly |
| Recommended | Yes, together with CAPI | Yes, together with the Pixel |
4 ways to set up the Conversions API
1. Partner integration (easiest)
If your store runs on Shopify or WooCommerce, use Meta’s official integration for that platform. It sends server events for you, usually in a few clicks.
2. Conversions API Gateway
A Meta-provided gateway you host in your own cloud account. Good when you want server-side events without writing code.
3. Your tag manager’s server container
If you already use a server-side tag manager, you can forward events to Meta from there.
4. Direct API integration
Your developers send events to the Conversions API endpoint themselves. Most flexible, most work. See Meta’s Conversions API documentation.
Deduplication: don’t count conversions twice
When both the Pixel and CAPI send the same purchase, Meta needs to know it’s one event. Send:
- the same
event_name(for example,Purchase) from both, and - the same unique
event_id(for example, your order ID) from both.
Meta keeps one and discards the duplicate. Without this, your results can look inflated and optimisation suffers.
What is Event Match Quality (EMQ)?
EMQ appears in Events Manager for each event, on a 0 to 10 scale. It reflects how well the customer information you send can be matched to Meta accounts. More matches mean Meta can attribute more conversions and find more people like your buyers.
How to improve your Event Match Quality
Send as many of these customer information parameters as you legitimately can with each server event:
| Parameter | What it is | Hash it? |
|---|---|---|
em | Email address | Yes (SHA-256, lower-cased, trimmed) |
ph | Phone number with country code | Yes (SHA-256, digits only) |
fn / ln | First / last name | Yes (SHA-256) |
external_id | Your own customer ID | Recommended to hash |
client_ip_address | Visitor’s IP | No |
client_user_agent | Visitor’s browser user agent | No |
fbp | Meta browser ID cookie | No |
fbc | Meta click ID (from fbclid) | No |
Practical steps:
- Capture email and phone early: at checkout or on the lead form, and send them with the event.
- Pass
fbpandfbcfrom the browser to your server so server events can be linked to ad clicks. - Send IP and user agent with every server event.
- Normalise before hashing: lower-case emails, strip spaces and symbols from phone numbers, include the country code.
- Fix your most valuable events first: Purchase and Lead matter more than PageView.
- Re-check EMQ in Events Manager a few days after each change.
Go further: send lead outcomes back to Meta
For lead-generation businesses, the most valuable signal isn’t the form fill, it’s which leads became customers. Sending those outcomes back to Meta (through CAPI or your CRM integration) teaches the algorithm to find more people like your actual buyers, not just form-fillers.
Common CAPI mistakes
- No deduplication, so purchases are double-counted.
- Unhashed personal data, which Meta rejects.
- Missing
fbc/fbp, which lowers match quality. - Sending events late: send them as close to real time as you can.
- Set-and-forget: a theme or checkout change can silently break events.
How Spotnxt helps
Spotnxt’s Signal Health shows your Pixel / CAPI event quality score, lists what’s broken and shows the fix. Its Lead Capture feature tracks leads through your stages and sends lead outcomes back to Meta. And because Spotnxt monitors campaigns 24/7, it flags tracking drops, such as purchase events suddenly falling, before they quietly inflate your CPA.
See Signal & Creative Health → · Read: Why did my Facebook CPA increase? →