Meta Conversions API (CAPI): what it is and how to set it up

If you run Meta ads, you’ve probably heard it’s a good thing to add the Conversions API to your Pixel setup. The reason is signal loss: ad blockers and browser limits stop some Pixel events before they reach Meta. This guide covers how the Conversions API works, which setup route fits you, and how consent carries over to server-side events.

In this guide:

• What is the Meta Conversions API?
• How the Conversions API works as server-side tracking
• Meta Pixel vs Conversions API: do you need both?
• Why use the Conversions API
• Conversions API and consent
• How to set up the Meta Conversions API
• Common Conversions API mistakes
• FAQ: Meta Conversions API

What is the Meta Conversions API?

The Meta Conversions API is a tool that sends data events, like purchases, leads, and sign-ups, from a server directly to Meta, rather than from the visitor’s browser through the Pixel. It’s how server-side tracking works for Meta ads on Facebook and Instagram. You’ll also see it called Meta CAPI, or by its old name, the Facebook Conversions API.

Server events land in the same place as browser events. According to Meta’s documentation, “Server events are linked to a dataset ID and are processed like events sent using the Meta Pixel.”

How the Conversions API works as server-side tracking

With the Pixel, the browser talks to Meta. With the Conversions API, a tracking server does. Here’s the path an event takes:

1. A visitor takes an action, like completing a purchase or submitting a form.
2. The event reaches a tracking server, sent from your site, your e-commerce platform, or your CRM.
3. The server hashes customer details. It converts email addresses, phone numbers, and names with SHA-256 before sending the event.
4. The server sends the event to Meta.
5. Meta matches the event to an account and attributes it to your ads.

What data the Conversions API sends

Every server event needs four fields: event_name, event_time, action_source, and user_data, according to Meta’s parameter reference. Website events also need the page URL (event_source_url), and you can add business data like currency and order value in custom_data.

The user_data field has strict rules. Meta requires SHA-256 hashing for email, phone, name, date of birth, and location fields. A few values must stay unhashed: IP address, user agent, and the fbp and fbc parameters. fbp is Meta’s browser ID from the _fbp cookie, and fbc is the click ID from the _fbc cookie or the fbclid link parameter.

Deduplication: how event_id stops double counting

If the Pixel and the Conversions API both report the same purchase, Meta needs to know it’s one purchase. That’s what deduplication does. In Meta’s words, “a Meta Pixel’s eventID must match the Conversion API’s event_id,” and the event names must match too. Meta only deduplicates events received within 48 hours of each other.

Meta Pixel vs Conversions API: do you need both?

You don’t need to choose. Meta recommends running both together:

“For optimal ad performance, we recommend that advertisers implement the Conversions API alongside their Meta Pixel.”

Meta, Conversions API documentation

Meta calls this redundant, and deduplication prevents double-counting.

Here’s how the two compare:

	Meta Pixel	Conversions API
Tracking type	Client-side	Server-side
Sends events from	The visitor’s browser	A tracking server
Affected by ad blockers and browser limits	Yes	Less so, so data is more accurate
Control over data before it’s sent	Limited	You choose which fields leave the server
Offline and CRM events	No	Yes
Setup effort	Code snippet or platform plugin	Varies by setup route

Why use the Conversions API

Meta reports that advertisers with a Conversions API setup for web events saw an average 17.8% lower cost per result than advertisers without one. The figure comes from Meta’s April 2026 announcement and, according to Meta’s video guide, an experiment run in November 2025 with 5,926 advertisers.

Beyond that headline, CAPI helps you:

• recover events the Pixel misses because of ad blockers or loading/connectivity issues, as long as the server event doesn’t depend on the blocked Pixel request (it’s sent from your backend or through a first-party endpoint),
• send offline and CRM conversions as well as website events,
• decide which data reaches Meta before it leaves the server,
• share events as they happen, which Meta says helps campaigns get the best results.

Conversions API and consent

Moving events to a server changes where data flows, but the consent requirement stays the same.

Server-side tracking doesn’t remove the consent requirement

European rules on tracking focus on storing or accessing information on a visitor’s device, not on which system sends the data onward. The European Data Protection Board (EDPB) makes this explicit in its Guidelines 2/2023 on the EU ePrivacy Directive: “the fact that the receiving entity might not be the entity instructing the sending of information does not preclude the application of Article 5(3) ePD.”

Meta’s own Business Tools Terms put the responsibility on advertisers. Where the law requires informed consent for cookies and device access, the EU being the example Meta gives, the terms require you, as the advertiser, to make sure, in a verifiable way, that people give the necessary consents before using Meta’s business tools. And regulators do look closely at Meta tracking, as the Austrian ruling on Meta’s Pixel showed.

How a visitor’s consent choice reaches server-side events

In a browser-only setup, a consent banner blocks the Pixel until the visitor agrees. Server-side, the consent choice has to travel with the event:

1. Your consent management platform records the visitor’s choice.
2. That signal goes with the event to the tracking server.
3. The server forwards only consented events to Meta.

For visitors in certain US states, Meta also offers Limited Data Use, a flag that restricts how Meta processes events under US state privacy laws. It works for both Pixel and Conversions API events, and you have to turn it on yourself.

How to set up the Meta Conversions API

Meta’s video guide walks through the main setup routes. The right one depends on how complex your tracking is and who runs the server-side part:

Option	Good for	What it takes
Meta’s one-click setup	Simple websites that just want CAPI switched on	A few clicks in Events Manager
Your ecommerce platform’s integration	Shopify and other online stores	Turning on a setting in your store
A server-side tracking tool	Teams that want control over events and consent, to send data to several marketing platforms or for data enrichment	Connecting the tool, while the provider runs the server, like iubenda
Server-side Google Tag Manager	Teams already using Google Tag Manager	A tagging server, run by your team or a hosting provider
Direct integration	Custom setups	Developer team’s help

Meta’s one-click setup vs a custom setup

Meta’s one-click setup is free and needs no code, according to Meta. It’s aimed at advertisers with low event coverage, and existing partner or custom setups see no change.

The one-click setup is a good fit for simpler setups. For more complex configurations, where you need control over events, data, and consent, a direct integration or a server-side tracking tool is the better fit.

As of October 2026, here’s how it compares:

	Meta’s one-click setup	Custom or partner setup
Events sent	Mirrors what the Pixel sends	You choose
Parameters per event	Whatever the Pixel sends	You choose and enrich
Filtering data before Meta	No	Yes
App and offline events	No, web only	Yes
Other ad platforms from the same tracking server	No, Meta only	Yes
Consent handling	Not documented by Meta	You control what’s forwarded

Setup checklist

1. Choose the events that matter, like purchases and leads.
2. In Events Manager, find your dataset ID and generate an access token.
3. Configure your chosen route.
4. Set up deduplication with matching event_id and event_name values.
5. Send test events and confirm Meta receives them.
6. Check your Event Match Quality score.
7. Confirm that only consented events reach Meta.

Common Conversions API mistakes

• Skipping deduplication: without matching event IDs, the Pixel and Meta CAPI can count the same conversion twice.
• Forwarding events without consent: server-side events need consent just like Pixel events.
• Getting hashing wrong: Meta requires hashed email and phone values, while IP address, user agent, fbp, and fbc must stay unhashed.
• Leaving out fbp and fbc: without them, match quality drops. When the Pixel is blocked, these cookies are often missing too, so match quality depends more on the hashed customer details you send.
• Sending events late: Meta accepts events up to seven days old, but real-time sharing gets better results.

Want the control of a custom setup without running a server? iubenda’s server-side tracking tool forwards events to the Meta Conversions API and other ad platforms only after checking each one against the visitor’s consent record.

FAQ: Meta Conversions API