Collect Pixel
Collect beacon via 1x1 pixel (GET).
This is the third fallback in the tracker's delivery chain, after sendBeacon (unload paths) and fetch keepalive POST (live paths). It fires when fetch() rejects, which most commonly happens when the renderer is torn down between an OPTIONS preflight response and the POST going out. Since v1.4.2 the live fetch path uses Content-Type text/plain and no custom headers, so it never preflights and this fallback should be rare; we still accept it for ad-blocker-bypass contexts and ancient browsers without fetch.
Identity (pvid/ver/lifecycle) is forwarded so the row collapses against any successfully-delivered POST for the same pageview via ReplacingMergeTree(version).
Authorization
bearerAuth API token generated from the fastmon dashboard (Account → API Token). Send as Authorization: Bearer fm_... or paste the full token (including the fm_ prefix) into the Authorize dialog.
In: header
Path Parameters
Response Body
application/json
application/json
curl -X GET "https://example.com/c/string"null{ "detail": [ { "loc": [ "string" ], "msg": "string", "type": "string", "input": null, "ctx": {} } ]}