The Ads API now includes the website_tag_id attribute in all—GET, POST, PUT, and DELETE—/1/accounts/:account_id/web_event_tags response objects. This corresponds to the ID shown in the Conversion tracking section of the Twitter Ads UI.
Twitter Ads API Team
$ twurl -H ads-api.twitter.com "/1/accounts/18ce54d4x5t/web_event_tags/nvmgx" | jq
{
"request": {
"params": {
"web_event_tag_id": "nvmgx",
"account_id": "18ce54d4x5t"
}
},
"data_type": "web_event_tag",
"data": {
"name": "site-visit-tag",
"view_through_window": 14,
"click_window": 30,
"embed_code": "<script src=\"//platform.twitter.com/oct.js\" type=\"text/javascript\"></script><script type=\"text/javascript\">twttr.conversion.trackPid('nw0es', { tw_sale_amount: 0, tw_order_quantity: 0 });</script><noscript><img height=\"1\" width=\"1\" style=\"display:none;\" alt=\"\" src=\"https://analytics.twitter.com/i/adsct?txn_id=nw0es&p_id=Twitter&tw_sale_amount=0&tw_order_quantity=0\" /><img height=\"1\" width=\"1\" style=\"display:none;\" alt=\"\" src=\"//t.co/i/adsct?txn_id=nw0es&p_id=Twitter&tw_sale_amount=0&tw_order_quantity=0\" /></noscript>",
"id": "nvmgx",
"retargeting_enabled": false,
"status": "DORMANT",
"type": "SITE_VISIT",
"website_tag_id": "nw0es",
"deleted": false
}
}