The Siloed Data Problem Every Merchant Faces

If you run an e-commerce business, your product data doesn't live in one place. Your core catalog is in Shopify or WooCommerce. Your margins sit in a finance spreadsheet. Stock levels update in your ERP. GTINs are buried in supplier portals. And promotional calendars live in Google Sheets or marketing tools.

When you build a product feed for Google Shopping or Meta, you're working with an incomplete picture. Missing GTINs mean lower ad eligibility. Missing margins mean you can't bid intelligently. Missing promotional flags mean your ads don't reflect your current sales.

This is the siloed data problem — and supplemental feeds are the solution.

What Is a Supplemental Feed?

A supplemental feed is an additional data source that you merge into your primary product feed. Instead of trying to cram every data point into your Shopify catalog (where it doesn't belong), you keep your external data in a Google Sheet and connect it to your feed via key matching.

The concept is simple:

Your primary feed has a unique key per product (SKU, product ID, or MPN)
Your supplemental sheet has the same key plus the extra columns you want to add
You map the keys together, and the supplemental data merges into your feed automatically

In FeedOn, this is done through Supplemental Data Mapping — a visual workflow where you connect a Google Sheet, preview the match, and merge the columns into your feed in minutes.

Use Case: GTIN Enrichment from Multiple Sources

GTINs (Global Trade Item Numbers) are a perfect example of siloed data. Google requires them for most product categories, but many merchants struggle because their GTINs are scattered across:

Supplier catalogs — provided as CSV or Excel files during onboarding
Brand portals — each brand has its own product database
GS1 databases — the official registry, but often requires manual lookup
Previous feed exports — you had GTINs in an old feed but lost them during a platform migration

With supplemental feeds, you consolidate GTINs from any of these sources into a single Google Sheet, key it by SKU or MPN, and merge the gtin column into your product feed. No need to edit thousands of products in Shopify. No manual copy-paste. The merge happens automatically every time your feed refreshes.

Beyond GTINs: What Else Can You Merge?

Once you understand the pattern, supplemental feeds unlock a wide range of enrichments:

Margin data — from your finance team's spreadsheet, so you can bid based on profitability
Stock age — from your warehouse or ERP, so you can promote new arrivals and clear aged inventory
Promotional labels — from your marketing calendar, so your ads reflect current sales and promotions
Sales velocity — from your analytics, so you can invest more in your best-selling products
Custom attributes — season codes, collection names, vendor tiers, material compositions — anything your catalog doesn't natively support

How It Works in FeedOn

Prepare your Google Sheet — ensure it has a key column (SKU, ID, or MPN) and the data columns you want to merge
Connect the sheet — paste the sheet URL into FeedOn's Supplemental Data Mapping page
Preview and map keys — FeedOn shows a preview of the sheet, and you select which column in the sheet matches which column in your feed
Select columns to merge — pick the columns you want added to your feed
Review match rate — FeedOn shows how many products matched and highlights unmatched keys so you can fix gaps
Save and refresh — the merged data is now part of your feed and available in feed rules, exports, and channel feeds

Stop Letting Silos Limit Your Ads

Every piece of product data that stays locked in a spreadsheet or ERP is a missed opportunity. Supplemental feeds let you bring all of it together — without touching your catalog, without custom development, and without waiting for your platform to add new fields.

Your data already exists. You just need to connect it.

Frequently Asked Questions

1. What is a supplemental feed in Google Merchant Center?

A supplemental feed is an additional data source that enhances or updates information in your primary product feed. It does not replace your main feed but adds missing attributes, enriches product data, or overrides specific fields (such as titles, custom labels, or seasonal tags) without changing your core e-commerce platform.

2. What does “siloed data” mean in e-commerce?

Siloed data refers to product information that exists in separate systems—such as ERP software, PIM systems, spreadsheets, marketing tools, or inventory databases—that are not directly connected. This fragmentation can lead to incomplete product feeds, inconsistent data, and reduced campaign performance.

3. How do supplemental feeds help solve siloed data issues?

Supplemental feeds allow you to merge data from different sources into your main product feed inside Google Merchant Center. For example, you can:

Add missing GTINs from a spreadsheet
Enrich titles with SEO keywords
Assign custom labels for margin tiers
Update seasonal or promotional attributes

This enables centralized optimization without restructuring your backend systems.

4. When should I use a supplemental feed instead of editing my primary feed?

Use a supplemental feed when:

Your main e-commerce platform limits data customization
You want to test optimized titles without changing your website
Marketing teams need control over campaign segmentation
You need to add attributes from external sources

It’s ideal for flexibility and experimentation without disrupting your core product database.

5. What kind of data can be added through supplemental feeds?

You can add or modify:

Product titles and descriptions
Custom labels (e.g., best-sellers, high-margin products)
Missing GTINs or MPNs
Sale prices
Google product categories
Additional attributes like material, pattern, or gender

The key requirement is that the supplemental feed must match products using a consistent ID.

6. Do supplemental feeds affect SEO or my website content?

No, supplemental feeds only affect how your products appear within Google Merchant Center and Shopping campaigns. They do not change your website content unless you manually update your store. This makes them a powerful tool for feed optimization without impacting your on-site SEO or user experience.

How Supplemental Feeds Solve the Siloed Data Problem in E-Commerce