The X Conversion API (CAPI) lets Cometly send your conversion events directly to X server-to-server, so X can attribute and optimize your campaigns even when browser-based pixel tracking is blocked or incomplete. This sends the events you've already tracked in Cometly back to X's Events Manager, matched to the ad click that drove them.
This article walks you through turning it on and mapping your events.
How it works
X CAPI is attribution-aware. When Cometly records a conversion, it looks for the X ad click that drove it (via X's click ID, twclid, and the Comet URL parameters on your ads), then sends the event to the X Pixel attached to that ad.
A visitor clicks your X ad and converts on your site.
Cometly attributes the conversion to that ad and its X Pixel.
Cometly sends the mapped event to X's Conversion API server-to-server.
For an event to be sent, the Cometly event must be mapped to an X Events Manager event (see Step 4). Events you don't map are never sent.
Note: Unlike some integrations, X CAPI does not require you to paste an API token. It uses the same X Ads connection you authorized when you connected the channel — so make sure X is connected first.
Before you start
An active X Ads account connected in Cometly (Integrations → X).
Your X Pixel installed on your site and at least one manually-created event in X Ads Manager under Tools → Events Manager (Cometly can only map events that have their own event tag — the auto-created standard events can't receive CAPI data).
Your ads should carry the Comet URL parameters from the X setup template so conversions can be attributed to the right ad. X expands its dynamic parameters automatically, so you can paste the template as-is:
comet_source=x&comet_campaign={{campaign_id}}&comet_ad_group={{adgroup_id}}&comet_ad_id={{ad_id}}
Step 1 — Open the Conversion API settings
Go to Events Manager, find X Ads, and open its Conversion API settings.
Step 2 — Choose a data-sharing mode
At the top you'll see the Master Data Sharing Settings. Pick one:
Turn off data sharing — no events are sent to X.
Send only attributed events (Recommended) send only events Cometly can attribute to an X ad click.
Send all events — send all events, including unattributed ones.
These settings apply to all events by default. You can override them per-event later using Custom Rules.
Step 3 — Set your default pixel and default account
Under Configure default pixels, enter the X Pixel ID for each ad account. You can find it in X Ads Manager under Tools → Events Manager (Cometly will pre-fill this for you once it loads your account's events).
Then select the default X account — this is the account used when an event can't be attributed to a specific ad account.
Step 4 — Map your events to X conversions
X requires an Events Manager event for each conversion. Select an X account to load its events, then map each Cometly event to the matching X event in the dropdown.
To add a new event, create it in X Ads Manager under Tools → Events Manager → "Add events" — it will appear here on the next load.
If Cometly can't load your account's events (or the account has no eligible events), you can paste the X event ID manually.
Click Save event map when you're done.
Step 5 — Save
Click Save to activate your Conversion API settings.
Event mapping rules
Mappings are per X ad account. Select each account and map its events separately.
Multiple Cometly events can map to the same X event.
Only mapped events are sent. If a Cometly event isn't mapped to an X event, it will never be sent to X.
Custom Rules let you override the Master Settings for specific events (for example, send one event even though the master mode is "attributed only").
Good to know
Once active, Cometly begins sending mapped conversions to X going forward — it does not backfill past events.
By default, Cometly auto-routes each conversion to the X Pixel attached to the ad that drove it. This keeps your per-campaign reporting in X accurate and is the correct behavior for nearly all accounts.
The Advanced → Force all events to a single pixel option overrides auto-routing and sends every conversion to your default account's pixel. Only use it if you've consolidated to a single pixel, or X support/your agency told you to. Forcing the wrong pixel can break attribution and is hard to reverse.
Troubleshooting
No conversions showing up in X Events Manager
Confirm your data-sharing mode isn't set to "Turn off data sharing."
Confirm the Cometly event is mapped to an X event (Step 4) — unmapped events are never sent.
Confirm your ads carry the Comet URL parameters so conversions can be attributed.
"Failed to load X events for this account"
Cometly couldn't reach X's Events Manager for that account. You can still paste the X event ID manually, or try reconnecting the X channel under Integrations.
My event isn't in the dropdown
Only manually-created Events Manager events appear. Create the event in X Ads Manager (Tools → Events Manager → Add events), then reload the mapping page.
I can't enter a pixel / the field is empty
Enter your X Pixel ID from X Ads Manager (Tools → Events Manager). A pixel is required on the default account before you can enable CAPI.