Reddit launched its Conversions API in 2023 and it is still maturing. Three specific quirks catch teams during implementation.

Quirk 1: pixel_id is hex, not numeric

Reddit's pixel IDs are hex strings (e.g., a2_abc123def456). The "a2_" prefix is required and easy to miss.

Quirk 2: events use uuid, not event_id

Reddit's dedup field is uuid. Same logic as event_id elsewhere, different field name.

Quirk 3: limited token scope

Tokens are tied to specific ad accounts. Multiple accounts means multiple tokens.

In sGTM

const event = {
  test_mode: data.testMode || false,
  events: [{
    event_at: new Date().toISOString(),
    event_type: { tracking_type: data.eventType },
    user: { email: data.hashedEmail, external_id: data.hashedExternalId },
    event_metadata: { uuid: data.eventId, currency: data.currency, value_decimal: data.value }
  }]
};
sendHttpRequest('https://ads-api.reddit.com/api/v2.0/conversions/events/' + data.pixelId, {
  method: 'POST',
  body: JSON.stringify(event),
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer ' + data.accessToken
  }
});

Reddit matches on email and external_id. Click ID matching uses rdt_cid; capture and forward following the click ID pattern.