Facebook Conversion API (CAPI) Explained For Beginners [in 2021]

The iOS 14 update was just the last big negative hit on traditional cookie-based tracking that is still the only comprehensive solution for Facebook ads tracking. However, as Facebook Pixel gets blocked more frequently, and the data we get from the Facebook Pixel gets more and more unreliable, advertisers have to find new ways to report and attribute conversions to their Facebook advertising campaigns. That is why Facebook has developed Facebook Conversion API (CAPI).

In this beginner guide, we are going to explain the most important thing you have to know about Facebook Conversion API (used to be called Facebook Server-side API) that is the new way how you can track your bottom of the funnel type conversions. Among others we are going to cover:

  • what is Facebook Conversion API?
  • why you should implement Facebook Conversion API?
  • How does Facebook Conversion API work?
  • How to set up Conversion API? (2 methods)
    • how to set up Facebook CAPI manually
    • how set up conversion API with a Partner Integration
  • Does your business need to use Conversion API?

By the way, if you want to make sure that the tracking on your website is set up correctly for Facebook ads campaigns, we highly recommend to get our Facebook Pixel and Conversion API Tracking Checklist template that you can use to audit your own or your client’s website existing tracking implementation. If you are lucky, you might still be able to get it for free, here:

Facebook Pixel and CAPI Checklist

What is Facebook Conversion API?

Facebook Conversion API is a tool developed by Facebook which you can use to send offline and web events directly from your servers to Facebook servers. Facebook CAPI is not a substitute but rather a complementary tool to Facebook Pixel so you can improve your conversion data that is attributed and reported for your Facebook ad campaigns.

As the Facebook Pixel based tracking is becoming more unreliable, Facebook Conversion API (used be called Facebook Server-side API) can help you improve the accuracy of your conversion events so not only you get more accurate data in your Facebook ad reporting area, but Facebook can also use more accurate datasets to optimize your Facebook ads campaigns.

Why you should implement Facebook Conversion API?

As we have already mentioned the main reason why Facebook Conversion API has been developed is that Facebook Pixel tracking although still a solution that works and that you should have, has become more unreliable because the of the following reasons:

  1. Use of Ad blockers: More and more users started to use Facebook ad blockers. And this is not only an issue because your Facebook and Instagram ads won’t get shown to users who use a really aggressive adblocker. But it will all prevent the Facebook Pixel from tracking Standard Facebook Events and Custom Events as well.
  2. Browsers like Safari and Mozilla and other web browsers put a really huge emphasis on user privacy, so they make it really easy to block tracking solutions like Facebook Pixel.
  3. Safari also deletes the cookie after 7 days that makes conversion attribution after 7 days impossible with traditional cookie-based tracking like Facebook Pixel
  4. iOS 14 update. As we have explained in our post about the iOS update effects on Facebook advertisers, from now on, app users on iOS14 have to explicitly allow Facebook for tracking them on 3rd party websites. It is expected that a lot of users won’t allow for Facebook to track them. This will lead to huge data loss and many related issues to Facebook advertisers.

All of these led to less attributed conversion to Facebook ad campaigns which means that in some cases it is not rare that less than 80% of all conversion gets reported to Facebook via the Facebook Pixel (and this was before the iOS14 update).

However, as the idea behind Facebook Conversion API is that Conversion events are not sent via the browser but directly from your server to Facebook’s server the issues, we have summarized above won’t have any negative effect on attributing Facebook conversions with the CAPI.

So when you implement Facebook Conversion API:

  1. More conversion data will be accurately reported to Facebook so you can optimize your campaigns on better data that will lead to better optimization decisions
  2. Facebook can use this better data to optimize your Facebook ads more effectively
  3. The size of your Facebook Custom Audiences will be bigger, the quality better:
    1. Which will lead to better Facebook retargeting campaigns
    2. and better Facebook Lookalike Audiences based campaigns
  4. You can evaluate your Facebook ads over ROI and ROAS more accurately that will lead to better marketing and ad buying budget allocations

Facebook Conversion API for attributing offline conversions

Last but not least, it is important to know that Conversion API can also be used to upload offline conversions to Facebook. If you are running a huge offline retail operation and regularly run in-store Facebook ads campaigns, then this way you could upload all your offline conversion data as well and match with Facebook database to see how effective your in-store campaigns are.

How does the Conversion API work?

As I am not a developer myself and it is not that important for marketers to know the technical details of Conversion API anyway I don’t want to get really deep into how Facebook Conversion API works and how it sends data from your server to Facebook servers.

(If you are more technical, start the reasoing here: https://developers.facebook.com/docs/marketing-api/conversions-api/)

But, you should at least understand how the conversion data gets shared with Facebook Pixel using Conversion API. The easiest way to show this is via an example:

  1. So let’s say that someone purchases on your website. This ‘Purchase’ conversion event with all the purchase information (value, currency, time, products, etc.) and the associated customer data (email, phone number, user agent, IP) is recorded on your server.
  2. This data is then shared from your server with Facebook’s server using Facebook Conversion API. Then Facebook will try to identify and connect the user
  3. Facebook will also check if this specific purchase event was also tracked by the Facebook Pixel
  4. If the FB Pixel also tracked this user then Facebook automatically deduplicates the data so only one purchase will be reported

It is also important to understand that Facebook Conversion API only works with bottom of the funnel data, where the customer or the potential customer has provided you with at least an email or other unique identifier. So currently, you can’t use this to improve the accuracy of your Facebook view content events, as usually, customers don’t provide you with an email address just to read an article or view a product page.

How does the Conversion API work with the Facebook Pixel?

As we have already mentioned in the previous Purchase conversion example, Facebook will always deduplicate Facebook Conversion API and Facebook Pixel Events. This means that if you implement Conversion API tracking as well, you don’t have to worry about your conversion data being duplicated if both CAPI and FB Pixel records a conversion.

Facebook does this by checking the event ID and the so-called Event ID parameters and if the events were received on the same Pixel ID and within the 48 hours then the Events get deduplicated.

If you want to learn more about event deduplication with Facebook Conversion API and Pixel, you can get more details here.

How to Set Up Facebook Conversion API?

Currently, there are two main ways how you set up Conversion API for your website. You can either use a partner integration that is provided by Facebook that makes the complete technical process easy and the implementation possible for marketers as well. Or you can work with a developer to implement the Facebook Conversion API manually which will definitely help you to get a more customized solution.

Facebook Conversion API Partner integrations

If you are using a popular e-commerce platform like Shopify or WordPress-based WooCommerce, then you can easily use the Partner Integrations that Facebook provides for CAPI. In these cases, you just have to go through some preconfigured steps.

Set up Facebook Conversion API with Partner Integrations

It is still not just a click of a button, but it is still easier and can be implemented without a help of a developer. (and 100% free as well.)

Manual Setup of Conversion API with a developer

If you have the resources to work with an in-house or freelance developer and you can’t use any partner integration that is provided by Facebook for Conversion API, then you can also manually set up the Conversion API with the help of a developer.

This process is definitely not an easy one, so you really need technical knowledge and preferably some experience with Facebook ads products. If you need to send more information to your developer on how he or she can set Conversion API for your website, you can read more about it here: https://developers.facebook.com/docs/marketing-api/conversions-api/

You can also check out this method of setting up the Facebook Conversion API that seems quite easy and it doesn’t require developer input:

Test Conversion API Server Events in Facebook Events Manager

Whichever method you used to implement Facebook Conversion API for your website, before you would set your project status to done, it is of course a must-have to test if the Conversion API is working correctly and Facebook receives the server events in the correct format.

Just like with Facebook Pixel Events, you can use the Test Events feature of Facebook Events Manager to test if you are sending in the server events the right way.

Do my business/my client need server-side tracking on Facebook?

I think there are three cases here if I want to give you a not too general answer to this question. Let’s differentiate between small businesses and enterprise businesses. And businesses that use a popular e-commerce platform to run their e-commerce website and businesses that use a custom coded system.

If you are a small business and your online advertising is heavily Facebook-driven and you are using an e-commerce platform that makes it easy to implement Conversion API with partner integration then it is a no-brainer to set up Facebook Conversion API for your website.

Even if you have limited resources, this should be a pretty easy thanks to Facebook’s Partner integrations.

If you are working for an enterprise company with huge resources then even if the website is custom coded if Facebook advertising plays an important role in your marketing activities then you should dedicate the necessary resources to manually set up Facebook CAPI.

The only definite case where we wouldn’t put time and resources into implementing Conversion API:

  • If you are a small business with very limited resources
  • Your e-commerce site is not built on a popular e-commerce platform or custom coded, so you can’t use Facebook’s partner integration
  • Facebook ads are not the primary way how you drive traffic to your website.

If all of these are true to your business, you might get a better return, if you were to focus your efforts and put your resources into other projects. Facebook Pixel is getting less accurate, but it is still an okay way to track your user actions that are happening in your website and it is still easier to manually install the Pixel and set up the FB Pixel Events with Google Tag Manager for instance.

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