Is there a Google offline conversion API? What to use in 2026

Yes. Google's route for sending offline conversions to Google Ads is now the Data Manager API, and Google has asked new integrations since June 2026 to use it instead of the older offline upload calls in the Google Ads API. Check the current Google documentation for the exact rules that apply to your account.

If you are building or buying something today, that is the one to look at first.

Some background, plainly. For years, people uploaded offline conversions through the Google Ads API, or by importing a file. That still exists in the interface, but Google announced that offline conversion imports and enhanced conversions for leads would move to the Data Manager API, with new use of the old route being blocked from June 2026. Whether your account is affected depends on when it last used the old route, so verify this in Google's own notes.

What is the Data Manager API? It is a single Google API for sending first-party data into Google's advertising products. Conversions are one of its data types, next to audience lists. It was released in late 2025.

So what do you need to send? For a lead that turns into a customer, you have three common ways to tie the sale back to the ad. The first is the click ID, the gclid, or wbraid and gbraid on some devices. The second is enhanced conversions for leads, which uses a hashed email or phone number you collected on the form. The third is a mix of both. Google ignores uploads that come too long after the click, and the window for click IDs is 90 days. Enhanced conversions for leads has its own shorter window, 63 days as I understand it, so check current documentation.

Here is a made-up example. A business called Harbor and Vine gets a lead from a search ad on the first of the month. The visitor leaves a phone number and email. Five weeks later the sale closes in the CRM. If Harbor and Vine saved the gclid when the lead arrived, or kept the hashed email, they can report the sale back to Google Ads with its value, well inside both windows.

What goes wrong? Three things, mostly. The click ID was never saved, because the form landed on a page that dropped it. The conversion action in Google Ads is set to the wrong type. Or the upload is late, past the window, and Google quietly ignores it. Also, Google Ads conversion actions may start as secondary, which means they do not drive bidding until you change that.

Another limit worth stating: Google does not always tell you row by row why an upload was refused, so you need your own record of what you sent and when.

Do you need to code against the API? Not necessarily. Some ad platforms, CRMs and tools handle the Data Manager API for you. What you must decide is what to send, when, and how to match it back to the click.

For reference, DataCops sends offline conversions to Google Ads, along with Meta, TikTok and LinkedIn, and keeps a per-row delivery log. It does not yet read back Google's per-row rejections.

Are you moving an old upload over, or setting up your first offline conversion?