Conversions API (CAPI)

Conversions API (CAPI) is a Meta tool that lets a business send events such as purchases, form submissions and sign-ups straight from its own server, CRM or app to Meta, instead of relying only on the Meta Pixel running in the browser. Meta uses this data to measure conversions and optimize ad delivery.

What is Conversions API?

The Pixel is code that runs in the customer’s browser, so it loses signal easily: ad blockers, browsers that restrict cookies, patchy connections, customers closing the tab before the thank-you page finishes loading. CAPI sends the same kinds of events from the business’s server side, independent of the browser.

According to Meta’s documentation, CAPI connects an advertiser’s marketing data (website events, app events, business messaging events, offline conversions) from a server, website platform, app or CRM to Meta’s systems to optimize targeting, lower cost per result and measure outcomes. Server events are linked to a dataset and processed the same way as Pixel events (Meta for Developers, Conversions API, September 2026).

The name CAPI usually refers to Meta, but other platforms have tools built on the same idea. TikTok has the Events API and recommends running it alongside its Pixel (TikTok Business Help Center, About Events API, accessed October 2026). Google has Enhanced conversions, which sends SHA256-hashed customer data to supplement the conversion tag (Google Ads Help, About enhanced conversions, accessed October 2026).

Why CAPI matters for businesses in Vietnam

In Vietnam, many orders are closed over Messenger, Zalo (a Vietnamese messaging app) or the phone. The Pixel only sees that a customer tapped to message or left a phone number. Whether that person bought anything lives in the CRM or in the sales team’s Excel file. If that outcome never gets sent back, Meta optimizes for the people most likely to leave a number, who are not necessarily buyers. With CAPI, the business sends events such as “qualified lead” or “deposit paid” back to Meta so the system learns the right goal. That signal matters even more now that Meta, with its Andromeda system, automates most of the targeting.

How to set up CAPI

1. Pick an integration method. If the website already has the Pixel, Meta lets you set up CAPI for website events in Events Manager with no code. The other routes are a partner platform or a direct server integration.
2. Send hashed customer information with each event. Email and phone number must be hashed with SHA256. Phone numbers need symbols and the leading zero removed and the country code added, so 0901234567 becomes 84901234567 (Meta for Developers, Customer Information Parameters, January 2026).
3. Prevent double counting. Meta recommends running CAPI alongside the Pixel and calls this a “redundant setup”. In that case, the same event must carry the same event_id and event name on both sides so Meta can drop the duplicate (Meta for Developers, Deduplicate Pixel and Server Events, June 2026).
4. Test with the Test Events tool and track the Event Match Quality score in Events Manager.

Meta Pixel vs. Conversions API

FAQ

Once I have CAPI, can I remove the Pixel?

Meta recommends using both with deduplication set up. If a business does not send the same event through both channels, that event needs no deduplication.

Do I need customer consent to use CAPI?

Yes. CAPI only changes the delivery route. What gets sent is still the customer’s email and phone number. Vietnam’s Personal Data Protection Law No. 91/2025/QH15 took effect on January 1, 2026, so the safest approach is to send data only for customers who have agreed to its use for advertising. See also first-party data.

If most of your orders close over messaging or the phone and no CRM events are flowing back to Meta yet, Adtek’s Lead Generation team can review your data flow with you. Reach us through the contact page.