Network request reference · Google Analytics 4

GA4 Measurement Protocol /mp/collect

GA4's documented server-to-server API for sending events, such as offline purchases, into a GA4 property.

The request at a glance

Request: POST https://www.google-analytics.com/mp/collect https://region1.google-analytics.com/mp/collect
Sent by: Google Analytics 4
Typically triggered by: Server-side code posting events
Related cookies: _ga

What this request is

The Measurement Protocol is GA4's documented API for sending events from servers and apps rather than from the visitor's browser. It adds events to the same GA4 property as the website's tag.

Requests are authenticated with an API secret created in the GA4 interface. To tie server events to a website visitor, they reuse the client ID from the visitor's _ga cookie.

What typically triggers it

A back-end system recording an event the browser cannot see, such as an offline purchase, a refund or a subscription renewal.
Server-side integrations that send events on behalf of a website or app.

Important parameters

Parameter	What it means	Source
`api_secret`	Query parameter: the secret created in the GA4 interface for this data stream.	Vendor-documented
`measurement_id`	Query parameter: the web stream's measurement ID (G-XXXXXXX).	Vendor-documented
`client_id`	Body field: identifies the browser, normally taken from the _ga cookie.	Vendor-documented
`user_id`	Optional body field: your own ID for a signed-in user.	Vendor-documented
`events`	Body field: up to 25 events, each with a name and params such as session_id and engagement_time_msec.	Vendor-documented
`timestamp_micros`	Optional body field: when the event happened.	Vendor-documented

How to find it on a site

Open the site in Chrome, open DevTools (F12, or Cmd+Option+I on a Mac) and go to the Network tab.
Reload the page and type mp/collect into the filter box.
Click a matching request and open Payload to read its parameters. Some may be in the request body rather than the URL.
You usually won't see this request in the browser, because it is sent from servers. Google provides a validation endpoint at /debug/mp/collect for testing payloads.

Sources

Google for Developers: GA4 Measurement Protocol reference

The endpoint, the sender and the parameters marked vendor-documented were checked against the sources above on September 27, 2026. Browse all network requests.

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