A product feed is a structured file, or a stream of records through an application programming interface (API), in which a retailer describes every item it sells: an identifier, a title, a description, a landing page address, an image, a price and whether the item is in stock. Shopping ads, marketplaces, social platforms and, more recently, artificial intelligence (AI) assistants do not crawl a shop to build their listings from scratch. They read the feed, check it, and assemble ads and product cards from its fields. It exists because a catalogue of 50,000 items cannot be advertised by hand, and each platform needs the facts in a predictable shape.

How a feed is built and read

At its simplest, a feed is a spreadsheet. Each row is one product, each column an attribute, and the first row names the attributes. Google, Microsoft and Meta all accept tab-separated or comma-separated text files. They also accept XML, the markup language used for syndication: Google's Merchant Center takes RSS 2.0 and Atom 1.0 files, and every attribute in an XML file must carry a g: prefix declared through the namespace http://base.google.com/ns/1.0, or Google ignores it, according to its RSS 2.0 specification page. The namespace still points to Google Base, where the format began.

A minimal record for a jacket might read: id JK-1042, title "Men's waterproof shell jacket - navy, size M", link to the product page, image_link to a photograph, availability in_stock, price 129.00 GBP, brand, and a Global Trade Item Number (GTIN), the barcode number assigned through GS1. According to Google's Merchant Center Help documentation, titles may run to 150 characters and descriptions to 5,000. Apparel adds colour, size, gender and age group, and each size of the same jacket shares an item_group_id so that variants are recognised as one product.

Delivery happens in one of four ways. The platform can fetch a file on a schedule from an HTTP, HTTPS, FTP or SFTP address; Google requires a scheduled file to be under 4 gigabytes. The merchant can upload a file by hand. A shop platform such as Shopify can push records through a connector. Large retailers use APIs, which update single items within minutes rather than resending the whole catalogue. Google's API-submitted products "expire either after 30 days or on their manually set expiration date, whichever comes first," according to its Google Ads developer guide, so even static catalogues must be refreshed.

On top of the primary feed sit supplemental feeds, which override selected fields without replacing the source. Microsoft extended supplemental feeds to all markets in September 2025, allowing titles, descriptions, custom labels, size, colour and promotion IDs to be edited, but not products to be added or deleted. Rules inside the platform or a third-party feed management tool perform similar rewrites: appending a brand to every title, mapping a shop's categories to Google's taxonomy, or filling custom_label fields.

Those labels matter to the buy side. Five custom_label attributes, numbered 0 to 4, let an advertiser segment products for bidding by margin, season or best-seller status. Google caps each at 1,000 unique values, and in June 2026 its specification began listing them for Demand Gen as well as Performance Max and Shopping.

Once ingested, the feed is validated. The platform crawls landing pages and compares them with the submitted price and availability, disapproving items that disagree. Approved items become eligible for auctions in which relevance comes from the text of titles and descriptions rather than bought keywords. On the sell side, the operator is the merchant's e-commerce, marketing or agency team; on the platform side, it is the catalogue system of Google, Microsoft, Meta, Amazon, TikTok, Pinterest or OpenAI.

From Google Base to dynamic ads

Comparison shopping sites took merchant files before any ad platform did, but the format most feeds now copy came from Google. Its product search, Froogle, launched in December 2002. Google Base, opened on November 16, 2005, accepted bulk uploads as RSS and Atom files with g: attributes, the convention still in use. Merchant Center replaced Google Base for product data in 2009, and the same year Google introduced Product Listing Ads, turning the feed into an advertising input. When Google Shopping became paid in 2012, a feed became a condition of appearing there at all.

Social platforms followed with retargeting. On February 17, 2015 Facebook introduced dynamic product ads, which rendered a product for each person at impression time from a catalogue the advertiser scheduled for daily or on-demand fetch, matched to product IDs fired by the site's pixel, according to Facebook's developer blog. The catalogue that powers what Meta now calls Advantage+ catalog ads feeds dynamic, collection and carousel formats, and holds verticals beyond retail, including hotels, flights and vehicles.

Marketplaces moved in the opposite direction, from flat files towards structured JSON. Amazon deprecated twelve XML and flat-file listings feed types in its Selling Partner API on March 18, 2024 and, after one postponement, removed them on June 30, 2025, directing sellers to the JSON_LISTINGS_FEED or the Listings Items API, according to Amazon's developer changelog. Google made a similar shift with the Merchant API, generally available in August 2025, which set August 18, 2026 as the shutdown date for the older Content API for Shopping.

The latest buyer is software. OpenAI published a product feed specification alongside Instant Checkout on September 29, 2025. Its format requires nine fields, including seller_name, and adds is_eligible_search and is_eligible_checkout flags; a separate path accepts files laid out on Google's specification, according to OpenAI's developer documentation.

Why the feed sits at the centre of retail advertising

The feed decides what feed-built ads can say. Google's Firas Yaghi said in April 2026 that Demand Gen campaigns using product feeds averaged a 33% conversion uplift over campaigns without them, and named GTIN submission and disapproval clearance as the areas merchants most neglect. Both figures are Google's own. Independent data points the same way: Smarter Ecommerce charted the share of Demand Gen campaigns using a feed rising from 16% in 2024 to 35% in 2026, without publishing its methodology.

AI shopping surfaces raise the stakes. Google has documented eight Merchant Center attributes tied to AI Mode or AI Overviews. Meta draws up to 20 video URLs per catalogue item for Dynamic Media, switched on by default from September 2025. Amazon opened Shop Direct to third-party feeds on March 11, 2026, after merchants objected to listings built from their sites without consent. A product absent from the feed is, for these systems, a product that does not exist.

Where feeds fail

Staleness is the oldest complaint. A feed is a snapshot; a shop's prices change hourly. In January 2026 the consultancy FeedArmy found that Google's automatic website import, described as refreshing every 24 hours, was serving product data nine to ten days old. Google's automatic item updates, which correct price and availability from page markup, "may not work well" for products whose price changes more than once a day, according to its help documentation.

Loss of control is a second. Platforms increasingly rewrite or replace what merchants supply. Google's smart cropping, on by default, crops and zooms feed images with no interface toggle, as FeedArmy and Kirk Williams of Zato Marketing documented in November 2025. Google's AI product import beta of May 2026 scans a site once and assigns identifiers itself, bypassing the feed entirely.

Fragmentation is a third. Each platform publishes its own field names and enumerations: OpenAI's availability field accepts pre_order and unknown, while Google's uses preorder and rejects unknown. Regional rules add more. Google made pickup cost and minimum order value mandatory across the UK, Switzerland and the European Economic Area from September 30, 2026 for merchants offering in-store pickup. Agencies sell feed optimisation largely because of this divergence; critics argue much of the work is rewriting the same facts for each gatekeeper.

Accountability is unsettled too. When OpenAI moved feeds into its ads business, none of its 32 advertising job openings in July 2026 was tied to feed accuracy or catalogue governance, leaving open who polices errors when an agent recommends a mispriced product.

Not the same as

  • Product catalogue: the set of products held inside a platform. The feed is the delivery mechanism that populates it; Meta uses "catalog" for the container and "data feed" for the file.
  • RSS feed: a syndication format for articles and podcasts. Google borrowed RSS as one product feed format, but a blog's RSS feed carries no prices or stock.
  • Consumer feed: the ranked stream of posts and videos a user scrolls in an app. Product feeds supply items that may appear inside it.
  • Dynamic creative optimisation (DCO): a technique that assembles ad variations from components and tests them. DCO often reads a product feed, but the feed itself contains no creative logic.

Recent developments

The feed is being repurposed from ad input to transaction input. OpenAI added product feeds to ChatGPT Ads Manager after shutting Instant Checkout in March 2026, accepting up to 1 million SKUs per advertiser and requiring a 100-product sample from new partners, according to reporting PPC Land cited. Google, meanwhile, opened a Merchant Center hub for its Universal Commerce Protocol, through which cart transfer and native checkout are rolling out to selected US merchants, with Canada and Australia expected in 2027. Meta extended catalog ads to Threads in October 2025, image and carousel formats only. As of October 2026, no cross-platform standard governs feeds; each buyer publishes its own specification, and most still accept Google's layout as a common denominator.

Timeline

  • December 2002 - Google launches Froogle, its product search engine.
  • November 16, 2005 - Google Base opens, accepting product uploads as RSS and Atom files with g: attributes.
  • 2009 - Merchant Center replaces Google Base for product data; Google launches Product Listing Ads as a US beta in November.
  • May 31, 2012 - Google announces that Product Search will become paid Google Shopping.
  • February 17, 2015 - Facebook introduces dynamic product ads built from scheduled product catalogue feeds.
  • March 18, 2024 - Amazon deprecates XML and flat-file listings feeds in the Selling Partner API.
  • April 2024 - Google updates the Merchant Center product data specification, adding AI-generated content disclosure attributes.
  • 2024 - Google renames feeds "data sources" in Merchant Center Next.
  • June 30, 2025 - Amazon removes XML and flat-file listings feeds, moving sellers to JSON.
  • August 2025 - Google's Merchant API reaches general availability.
  • September 2025 - Microsoft launches global supplemental feeds; Meta makes Dynamic Media the default for catalog ads.
  • September 29, 2025 - OpenAI and Stripe launch Instant Checkout with a product feed specification.
  • October 2025 - Meta brings Advantage+ catalog ads to Threads.
  • March 2026 - OpenAI shuts Instant Checkout; Amazon opens Shop Direct to third-party feeds on March 11.
  • June 2026 - Product feeds appear in ChatGPT Ads Manager; custom labels extend to Demand Gen.
  • August 18, 2026 - Google's Content API for Shopping reaches its shutdown date.
  • September 30, 2026 - Pickup cost and minimum order value become mandatory in the UK, Switzerland and EEA.
  • October 2026 - Google's UCP hub in Merchant Center rolls out to selected US merchants.

Summary

  • Who: Retailers, brands and marketplace sellers produce product feeds, often through agencies or feed management tools; Google, Microsoft, Meta, Amazon, TikTok, Pinterest and OpenAI consume them.
  • What: A structured file or API stream of product records, with identifiers, titles, prices, images, availability and category attributes, from which platforms build ads, listings and AI shopping answers.
  • When: The format took shape with Google Base in November 2005, became an advertising input with Product Listing Ads in 2009 and dynamic product ads in 2015, and was extended to AI agents from September 2025.
  • Where: Shopping ads, free listings, social catalogue ads, marketplaces, AI assistants and agent checkout systems, in every market these platforms serve, with regional attribute rules in places such as the UK and EEA.
  • Why: Platforms need predictable, machine-readable product facts at catalogue scale, and the quality and freshness of those facts now determine which products appear, at what price, across both paid and AI-driven surfaces.