ChatGPT ads conversion tracking on Shopify: the Conversions API

By the HonestTag team · Published October 31, 2026 · Updated November 11, 2026

ChatGPT Ads can take a purchase from the shopper's browser, from your server, or from both. A server that never records the ad click sends the purchase with no click to match.

Two ways to send a purchase

	Where the event is sent from	OpenAI's description
Measurement Pixel	The shopper's browser	"Measure actions that happen on your website."
Conversions API	Your server	"Send actions recorded by your server, such as confirmed orders."
Both	Browser and server	"Measure the same actions through both integrations, with shared event IDs to prevent duplicates."

Source: OpenAI's Conversion Tracking guide. Both routes identify your store's data source with a Pixel ID. OpenAI says the Conversions API helps you "Measure conversions without depending solely on browser event delivery," and that you can get a Pixel ID and Conversions API key "from the conversions tab in Ads Manager" (Conversions API).

The part a server cannot do alone: the click

OpenAI's attribution identifier for an ad click is called oppref, and the Measurement Pixel "captures oppref from the landing page URL" and keeps it in a first-party cookie for "30 days after the Pixel writes the cookie," a lifetime OpenAI says "Browser restrictions or clearing cookies can shorten" (Measurement Pixel).

A server sees the order, not the landing page. OpenAI is direct about it: "Unlike the pixel, the API does not capture oppref for you." OpenAI's click match uses that original oppref string, unmodified, when the server event has it (Conversions API). A server-side setup without it still sends purchases, but loses the click that brought the shopper in.

Rules that decide what ChatGPT Ads counts

• One purchase, one ID. "For deduplication, OpenAI uses your Pixel ID, event_name, and id. OpenAI uses the first event it receives for a matching key and ignores later duplicates." If the pixel and a server send the same order with different IDs, it counts twice.
• Seven days. An event's time "must be within the last 7 days and no more than 10 minutes in the future."
• OpenAI recommends sending all conversion events. That includes those without an oppref, "to incorporate view-through conversions in your campaign's performance metrics." View-through conversions use "a fixed one-day window after an eligible ad impression," and they "are not included in Conversions, which remains the click-through conversion total." Cost per Acquisition (CPA), post-click CVR, bidding, billing, and conversion optimization "also remain click-through-based."
• No raw customer details. OpenAI says to "trim leading and trailing whitespace and convert the value to lowercase" for an email address, and "Don't send raw email addresses, phone numbers, external IDs, first names, or last names."

Source for the four rules: OpenAI's Conversions API page. One more from its Conversion Tracking guide matters before you launch a campaign: "Custom events cannot be used for conversion optimization," and in a conversion-optimized campaign "the selected event setting also cannot be changed after creation." So a conversion-optimized campaign stays on the event it was created with.

What this means

Set the purchases ChatGPT Ads reports beside your Shopify orders for the same days. A count near double your orders points to two sources sending each order under different IDs: OpenAI ignores a later event only when the Pixel ID, event name and ID all match. A count short of your orders can come from a browser-only setup, which is what OpenAI offers the Conversions API to get past ("without depending solely on browser event delivery"), or from events sent more than 7 days after the purchase, outside OpenAI's limit. If purchases arrive but few land in Conversions, the total OpenAI keeps separate from view-through conversions, a server sending without oppref is a likely cause.

OpenAI says Conversions "remains the click-through conversion total" and that bidding, billing and conversion optimization "also remain click-through-based," so a doubled count tells the campaign its traffic converts better than it does, and a missing oppref can hide sales the ads did bring in.

On paid plans, HonestTag sends eligible orders from your Shopify online store, within the plan's delivery limit, each once, with an ID made from the order that stays the same on every retry, and passes oppref unchanged when its own pixel recorded one.

How HonestTag helps

On the free Mirror plan, HonestTag sends ChatGPT Ads no orders. On paid plans, HonestTag sends the verified orders from your Shopify online store to ChatGPT Ads through the Conversions API. It leaves out an order with no click reference, no email and no phone, one more than 7 days old, point of sale orders and subscription renewals, orders from other apps and sales channels unless you switch them on, and EU, EEA, UK and Swiss orders with no visitor record unless you asked HonestTag in writing to turn that gate off. You paste a Pixel ID and a Conversions API key on the OpenAI Ads card, and HonestTag checks the key with a validation-only test event, which OpenAI does not save, before it saves anything.

• The click comes with the order. HonestTag's own first-party pixel records oppref from the landing page, and when it recorded one, the purchase carries it unchanged, the way OpenAI asks.
• The same ID on every retry. Each order goes as one order_created event with an ID made from the order, the same on every retry.
• Matched on what the order holds. SHA-256 hashes of the buyer's email and phone, normalized the way OpenAI specifies, a hash of HonestTag's visitor ID as an external ID, plus the IP address and user agent Shopify recorded on the order.
• New customers, measured. With an optional Ads API key, HonestTag creates four goals, or uses ones you already have with the same name and event: HonestTag_Purchase on order_created, the only one of the four a conversion-optimized campaign can use, plus new-customer, returning-customer and first-click new-customer goals to attach to campaigns for measurement.
• Proof per order. On a sent order, the proof shows OpenAI Ads as the platform, the delivery status, the event ID and which goals were sent. HonestTag does not send ChatGPT Ads a refund; the refund is recorded in the order's proof.

If the OpenAI Measurement Pixel or another app already sends purchases to the same Pixel ID, HonestTag's event ID will not match theirs, so OpenAI counts the order twice. The full setup is in Connect ChatGPT Ads, and duplicate purchase events shows how to find every purchase source on a store.

Install HonestTag free from the Shopify App Store and see the Mirror plan.

Paid plans can send ChatGPT Ads your orders. A store's first paid plan includes one 21-day trial, once per store.

Frequently asked questions

Sources

• OpenAI: Conversions API, read October 29, 2026
• OpenAI: Conversion Tracking, read October 29, 2026
• OpenAI: Measurement Pixel, read October 29, 2026
• OpenAI: Supported Events, read October 29, 2026
• HonestTag: Connect ChatGPT Ads
• HonestTag pricing and plan limits