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TL;DR: Connect Shopify, build a feed under Content > Products, pick Classic or Personalized logic, filter out what you don't want, and drop a dynamic Product block into your templates. Then audit the silent killers: untracked inventory, deny policies, unpublished products, and slow collection syncs. Your catalog gates back in stock emails worth about $9.14 per send, so treat feed setup as revenue work, not admin work.
A Klaviyo product feed is a dynamic set of synced catalog products that auto-fills recommendation blocks in email and SMS for Shopify brands, using up to 90 days of shopper behavior to choose each item. That one sentence hides a lot of money. Klaviyo product feed setup takes maybe 20 minutes, but the catalog behind it decides whether your highest-earning automations fire at all.
Here's the stake. Back in stock emails average about $9.14 per send, the highest of any Klaviyo automation, according to BS&Co's Klaviyo benchmarks. Abandoned cart, the flow everyone obsesses over, earns $3.65 per recipient in Klaviyo's own benchmark data. Both depend on the same thing: a catalog with accurate price and inventory fields. When that catalog breaks, nothing errors out. Products just vanish from your emails, and revenue drops with no alarm attached.
This guide covers the full setup: what syncs from Shopify, how to build Classic and Personalized feeds, where to use them in flows, custom feeds for non-Shopify stores, and the four silent settings that quietly empty your recommendation blocks.
What is a product feed?
A product feed is a saved set of rules that pulls items from your Klaviyo catalog into message blocks. The catalog is the full product database synced from your store. The feed is the filtered slice of that catalog that actually appears in your emails, and one catalog can power dozens of feeds.
The distinction matters because it tells you where to look when things break. The catalog holds the raw data: items, variants, prices, inventory, images, and URLs. Feeds sit on top as rules, like "bestsellers under $50 from the Skincare collection." When products go missing from an email, the problem is almost always the catalog layer, not the feed rules.
One more reason to get this right in 2026: Klaviyo has extended dynamic product recommendations beyond email to SMS, mobile push, and WhatsApp. You build the catalog once, and it now feeds every channel you send on.
What syncs from Shopify?
The Shopify integration syncs product names, SKUs, tags, URLs, images, pricing, and variant data to Klaviyo in real time. Collections and categories move slower, re-syncing every 6 hours. You never upload a spreadsheet. The catalog builds and maintains itself once the integration connects.
That split cadence trips people up. Change a price and Klaviyo reflects it almost immediately. Create a new collection and it can take up to 6 hours to appear. There's a manual resync option in the Catalog tab, but it processes 25 items per page, which makes it a spot-fix for a few products, not a strategy for a 2,000 SKU store.
The practical rule: build collections at least a day before any feed or send depends on them. Then confirm the products show up under Content > Products before you schedule anything.
Klaviyo product feed setup
The build itself is short. Follow these steps in your account:
- Go to Content > Products, open the Product feeds tab, and click Create Product Feed.
- Name the feed for its job, like "Cross-sell: bestsellers under $75." You'll be picking it from a dropdown inside a template later, so make it obvious.
- Choose your logic. Classic feeds rank products by a fixed rule, such as bestsellers, newest, or random. Every recipient sees the same products.
- Or choose Personalized. Klaviyo scores products for each individual recipient using a 90-day lookback of what they viewed, carted, and bought, as outlined in Klaviyo's product feed documentation. Subscribers with no history get popular items as a fallback.
- Add filters. Restrict the feed to a category or collection, set a price floor or ceiling, and keep the in-stock filter on.
- Save. The feed is now available inside any email template.
Two filter tips from experience. Exclude gift cards, because they look strange in a recommendation grid. And set a price floor on cross-sell feeds so your algorithmic real estate doesn't push $4 accessories to a customer who just spent $200.
How do feeds go in emails?
Drag a Product block into your Klaviyo template, switch it to Dynamic, and select your feed as the source. Set the grid, such as two columns by two rows, and the block fills itself at send time with each recipient's recommended products.
The best homes for feeds are post-purchase cross-sells, browse abandonment follow-ups, win-backs, and a recommendation row at the bottom of newsletters. Those placements are where well-built email automations compound quietly, and a single feed row can lift clicks on otherwise plain email campaigns without any extra design work.
One warning that most guides skip: don't use a feed for abandoned cart contents. Cart emails need to show the exact items someone left behind, and that data comes from a dynamic table fed by the Checkout Started event, not from a feed. Feeds show related products, not their cart. Klaviyo's own community guidance draws the same line. The strongest cart emails use both: the event-driven cart table up top, a feed row below it labeled "You might also like."
Custom product feed setup
Not on Shopify or another supported integration? Klaviyo still accepts your catalog through a custom catalog feed. Per Klaviyo's developer documentation, the requirements are strict:
- A public HTTPS URL serving JSON or XML
- A file size under 100 MB
- Klaviyo re-syncs the feed every 6 hours
- Klaviyo support must finalize the connection before it goes live
Field mapping is where custom feeds succeed or fail. Map the item ID, title, URL, image, price, and inventory fields. Skip price and inventory mapping and you lock yourself out of back in stock and price drop flows entirely, which is where the real money sits. Plan around the 6-hour cadence too. If you run flash sales, price changes can lag by hours, so time your sends after a sync, not before one. On large catalogs, trim long description fields to stay under the 100 MB cap.
The silent feed killers
This is the section that separates a working setup from a profitable one. When a product drops out of a feed, Klaviyo shows no error, no warning, and no log entry. The block simply renders without it. Four settings cause most of these disappearances.
Track quantity turned off. Klaviyo auto-hides items that aren't inventory-tracked from every feed, a behavior confirmed repeatedly in Klaviyo's community forums. If a hero product isn't tracked in Shopify's inventory settings, it will never appear in a recommendation block.
Inventory policy set to deny. The moment stock hits zero on a product set to deny purchases, it reads as unavailable and vanishes from all feeds. Even if the restock lands tomorrow.
Product unpublished from the sales channel. Pull a product from your Online Store channel for a redesign and Klaviyo treats it as gone. It disappears from feeds the same day.
Collections lagging the 6-hour resync. Build a collection at 9 am, filter a feed by it, send at 10 am, and the block renders half-empty because Klaviyo hasn't seen the collection yet.
The diagnostic routine is simple. Search the item under Content > Products. Check its inventory tracking and publish status in Shopify. Force a manual resync if needed, remembering the 25 items per page limit. Then preview the email as a real profile with purchase history. These leaks are common enough that a Klaviyo audit starts with catalog health before touching a single flow.
Why do feeds gate revenue?
Because the catalog controls your highest-earning automations. Flows drive about 41% of email revenue from just 5.3% of sends, per Eightx's flow benchmarks, and the best performer of all, back in stock, only works when price and inventory fields are mapped. A broken catalog switches those flows off silently.
Run the numbers. BS&Co's benchmarks put back in stock at $9.14 per email with a 6.72% conversion rate, the highest of any Klaviyo automation. Klaviyo's abandoned cart benchmarks sit at a 50.5% open rate and $3.65 per recipient. Back in stock out-earns cart emails roughly 2.5x per message, and it's pure catalog plumbing. No inventory data, no flow. Price drop flows face the same gate, since they only trigger for in-stock items.
Zoom out and the case gets stronger. McKinsey research cited by Contentful found personalization drives a 5 to 15% revenue lift, and the fastest-growing companies earn 40% more from it than slow movers. Across the Shopify stores we manage at CartStrings, email attributes 32% of revenue on average, and catalog health is one of the first things we check when a store falls short of that number.
Your next step
Set up the feed, then protect it. Connect Shopify and confirm the catalog under Content > Products. Build one Classic bestseller feed and one Personalized feed. Drop them into post-purchase and browse abandonment flows, keep Checkout Started data for cart emails, and run the four silent killer checks monthly: inventory tracking on, deny policies reviewed, products published, collections synced before sends.
Do that and your catalog stops being a settings page and starts being the pipe your best automations drink from. If you'd rather have someone who does this daily confirm nothing is leaking, book a call with CartStrings and we'll walk your setup together. More hands-on Klaviyo guides live in our articles library.
Frequently Asked Questions
Does Klaviyo sync Shopify?
Yes. The integration automatically syncs product names, SKUs, tags, URLs, images, pricing, and variant data in real time. Collections and categories update on a slower 6-hour cycle. No manual product uploads are needed.
How often does Klaviyo sync?
Core Shopify product data syncs in real time as changes happen. Collections and categories re-sync every 6 hours, and custom catalog feeds are pulled on the same 6-hour cadence. A manual resync is available in the Catalog tab, but it processes 25 items per page.
Why are products missing?
Klaviyo hides products from feeds without showing any error. The usual causes are inventory tracking turned off in Shopify, an inventory policy of deny combined with zero stock, the product being unpublished from your sales channel, or a new collection that hasn't hit the 6-hour resync yet. Check the item under Content > Products, then verify its settings in Shopify.
Do carts need a feed?
No. Abandoned cart emails should pull exact cart contents from the Checkout Started event using a dynamic table. Product feeds are built for cross-sell and recommendations, not cart contents. Strong cart emails often use both, with the cart table first and a feed row below it.
Can I sync without Shopify?
Yes. Klaviyo accepts a custom catalog feed, which is a public HTTPS URL serving JSON or XML up to 100 MB. Klaviyo re-syncs it every 6 hours, and Klaviyo support must finalize the connection before your recommendations go live.
