> For the complete documentation index, see [llms.txt](https://docs.mediarithmics.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mediarithmics.io/connectors/destinations/meta/custom-audiences.md).

# Custom Audiences

Send offline hashed data to Meta technologies, including Facebook and Instagram, as a Custom Audience.

Meta Custom Audiences sends offline hashed data from mediarithmics to Meta technologies, including Facebook and Instagram. Because it is server-side, the data goes straight from mediarithmics' servers to Meta.

<table data-search="false"><thead><tr><th width="220">Connection</th><th></th></tr></thead><tbody><tr><td><strong>Type</strong></td><td>Server-side</td></tr><tr><td><strong>Category</strong></td><td><a href="/connectors/partner-types/social-and-retail-media.md">Social &#x26; retail media</a></td></tr><tr><td><strong>Identifiers sent</strong></td><td>Email identifiers, Mobile IDs, Profile data</td></tr><tr><td><strong>Authentication</strong></td><td>Meta Business partnership granted to mediarithmics</td></tr></tbody></table>

## Description

### What you can do with this connector

* Retarget identified - logged-in - visitors on Facebook and Instagram from a mediarithmics segment.
* Enrich a Meta Custom Audience that already exists.
* Reach users who have not visited your site recently, which the pixel route cannot do.

The industry match rate varies from **30% to 70%** depending on what you send. The **email hash** is the field that maximises it.

### Which identifiers are sent

* **Email identifiers**
* **Mobile IDs**
* **Profile data**

Meta's own [Custom Audiences guide](https://developers.facebook.com/docs/marketing-api/audiences/guides/custom-audiences#hash) lists the fields it handles.

Meta is reached by several connectors and they behave differently - [the comparison is on the Meta page](/connectors/destinations/meta.md).

## Connector setup

### Prerequisites

* A Meta Business Manager account.
* A **partnership with mediarithmics Business**, business ID `489958474732149`, granting rights sufficient to create audiences on your ad accounts - the *Annonceur de compte publicitaire* level.
* The list of Meta ad account IDs to synchronise audiences to.

### Authentication

The connection is a Meta Business partnership you grant. Meta documents it in [Share assets with a partner](https://www.facebook.com/business/help/1717412048538897).

### Setup steps

{% stepper %}
{% step %}
**Create the partnership with mediarithmics in Meta Business Manager.**

1. Log in to your Meta Business Manager account.
2. Click **User › Partners** in the left panel.
3. Select a partner, then **Add › Grant a partner access to your resources**.
4. Enter the mediarithmics Business ID `489958474732149` and click **Next**.
5. Select **Ad Accounts** in the left panel, tick the ad account you want to grant access to, select **Manage Campaigns**, and click **Save**.
   {% endstep %}

{% step %}
**Send your ad account list to your account manager.**
{% endstep %}

{% step %}
**Agree the data to send with your mediarithmics Solution Architect.**

They also handle the first configuration - data files and the rest.
{% endstep %}

{% step %}
**Select the Meta Custom Audiences connector and fill in its configuration.**

<table data-search="false"><thead><tr><th width="280">Field</th><th></th></tr></thead><tbody><tr><td><strong>Name</strong></td><td>Identifies the feed inside mediarithmics.</td></tr><tr><td><strong>Meta Ad Account ID</strong></td><td>The Meta ad account to synchronise the audience with.</td></tr><tr><td><strong>Compartments to use</strong></td><td>The compartments the CRM data comes from - for example <code>1111</code>, or <code>1111,2222,3333</code>. To send mobile IDs, add <code>MOBILE</code>, <code>MOBILE_AND</code> or <code>MOBILE_IOS</code> to the list, for example <code>1111,2222,MOBILE_AND</code>.</td></tr><tr><td><strong>Customer file source</strong></td><td>How the customer information was originally collected. <code>USER_PROVIDED_ONLY</code> - directly from customers. <code>PARTNER_PROVIDED_ONLY</code> - from partners such as agencies or data providers. <code>BOTH_USER_AND_PARTNER_PROVIDED</code> - both.</td></tr><tr><td><strong>Custom Audience ID</strong></td><td>An existing Custom Audience to enrich.</td></tr><tr><td><strong>Custom Audience name</strong></td><td>A specific name for the Custom Audience. Defaults to your mediarithmics segment name.</td></tr></tbody></table>
{% endstep %}
{% endstepper %}

Creating and activating the feed on a segment is covered in the **Audience & Activation** section, under *Activate your audiences › Send your first-party data to a destination*.

## Good to know

**Exits are communicated.** When a UserPoint in a segment synced with Meta through this connector is removed from that segment, or deleted in mediarithmics, the removal is sent to Meta and the user is removed from the Meta audience.

## FAQ

#### How do I get the best match rate?

Hash your data as **SHA-256**; Meta supports no other hashing mechanism. It is required for everything except External Identifiers, App User IDs, Page Scoped User IDs and Mobile Advertiser IDs.

Normalise before hashing. Only first name (FN) and last name (LN) support special characters and non-Roman alphabets, and even there the Roman-alphabet transliteration without special characters matches best. Meta's [Custom Audiences documentation](https://developers.facebook.com/docs/marketing-api/audiences/guides/custom-audiences?locale=en_US) has the detail.

{% hint style="warning" %}
If you activate on **both** Meta Custom Audiences and Google Ads Customer Match, remember that the data formats **before hashing** differ between the two. Talk to your account manager.
{% endhint %}

#### Where do I find my segment in the Meta console?

Look for the **technical name** of your segment, not its display name. Open **Edit** on the segment in mediarithmics to read it.

{% hint style="warning" %}
Historically mediarithmics assigned random technical names such as `alabama-burger`, and that is what you would search for in the Meta console. You can change the technical name to match your segment name - but **only before creating the feed to Meta**. Change it afterwards and you still have to search for the previous one.

The technical name must contain text characters only: no special or numeric characters.
{% endhint %}

Inside the Meta console, custom parameters for new Custom Conversions and Custom Audiences are now free-form entry rather than a dropdown. Type the exact standard or custom parameter name being shared with Meta.

#### Is it a problem to have several Meta pixels on my website?

Not necessarily - some businesses legitimately need more than one. When implementing your feed with your Meta pixel ID, check that the pixel fires correctly with the [Meta Pixel Helper](https://chromewebstore.google.com/detail/meta-pixel-helper/fdgfkebogiimcoedlicjlajpkdmockpc). Meta covers the topic in [Event tracking with multiple pixels](https://developers.facebook.com/ads/blog/post/v2/2017/11/28/event-tracking-with-multiple-pixels-tracksingle/).

#### What happens when a user leaves the segment?

The removal is sent to Meta and the user is taken out of the Meta audience. The same applies when the UserPoint is deleted in mediarithmics.

## Partner documentation

Meta documents its own platform at <https://developers.facebook.com/docs/marketing-api/audiences/>. Use it for anything that happens on the partner side of this connector: account setup, the fields the partner expects, and its own limits.


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