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Shopify complementary products are items shoppers are likely to buy alongside the product they're viewing — configured through Shopify's free Search & Discovery app and displayed on product pages as a targeted cross-sell block. For South African merchants competing in a market where online retail now accounts for nearly 10% of total retail spend, nudging a shopper to add one more item before checkout is one of the lowest-cost ways to grow revenue without increasing ad spend.
This guide covers exactly how to configure the feature, what your theme must support for the block to appear, and a decision table that tells you when the free native method is enough — and when it isn't. If you're already running Shopify product bundles, complementary product recommendations give you a second, lighter-touch cross-sell that works at the individual product level rather than requiring pre-packaged sets.
Quick Answer
Shopify complementary products are manually curated add-on suggestions assigned to individual listings through the free Shopify Search & Discovery app. Once assigned, they appear in a dedicated block on the product page — but only if your theme includes that block and the recommended item is in stock. Setup takes under 15 minutes per product; the main decisions are which items to pair and whether the native app's limitations (no analytics, no A/B testing, no bundle discount) justify a paid alternative for your store's size.
Jump to a section
What are they and how do they work?
Cross-sell vs related recommendations — the difference
How to install and configure Search & Discovery
Theme block and display requirements
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What Are Shopify Complementary Products?
Shopify complementary products are items "often bought in addition to a selected product" — the platform's own definition distinguishes them from related products, which are substitutes in the same category. A running shoe page showing a shoe-cleaning kit and athletic socks as complementary items is doing something different from showing alternative shoe styles as related items. Complementary items increase cart value; related items help shoppers who haven't decided yet.
Unlike Shopify related products, which the platform generates automatically using purchase history and collection relationships, complementary product recommendations are entirely manual. You decide, product by product, which items pair naturally. That manual control is both the strength and the limitation of the native feature.
Key point
Shopify complementary products are cross-sell suggestions you control entirely. The platform will not auto-generate them. If you don't configure them, the block either shows nothing or falls back to related products, depending on your theme.
Cross-Sell vs Related Recommendations: The Strategic Difference
The two recommendation types serve different purchase-stage goals, and confusing them leads to generic "you may also like" sections that convert poorly.
| Feature | Complementary (cross-sell) | Related (substitute) |
|---|---|---|
| Intent | Add to the same order | Compare before deciding |
| Typical placement | Near add-to-cart button | Below product details or footer |
| Shopify setup | Manual only via Search & Discovery | Manual or auto-generated |
| Shows when out of stock? | No — hidden automatically | Yes, if "continue selling" is on |
| Shopify app required? | Yes — Search & Discovery (free) | Yes — same app |
| Best for AOV | ✓ Direct add-on prompt | Less direct — can redirect away |
The stock-visibility rule catches many SA merchants off guard: complementary product recommendations hide automatically when the recommended item goes out of stock — even if you have "continue selling when out of stock" enabled. For stores with variable stock levels, this means a well-configured cross-sell section can go blank without warning. Audit your pairings when you run low on stock, or assign backup items for each hero product.
How to Install and Configure Search & Discovery
The Shopify Search & Discovery app is free and installs directly from the Shopify App Store. Configuring shopify complementary products through this app follows these steps:
- Install the app. Go to Shopify Admin → Apps → Shopify App Store, search "Shopify Search & Discovery" and click Add app. If you already have it installed, skip to step 3.
- Open Recommendations. Inside the app, navigate to the Recommendations tab in the left sidebar.
- Search for a product. Use the search bar to find the product you want to configure. You're setting recommendations for this product — the one a shopper is viewing.
- Add complementary items. Select the items you want to suggest as add-ons. You can assign up to 10 Shopify complementary items per product. Drag to reorder them by priority. How many appear on the storefront is controlled by the theme block's Maximum products to show field — not the app itself.
- Save. Changes go live immediately; there's no publish step.
- Add the block to your theme. This step is separate and is covered in the section below — without it, your configuration won't appear on the storefront.
Practical note: Setup per product takes 2–5 minutes once you know your pairings. The bottleneck is deciding which items to pair, not the configuration itself. If you have 200+ active listings, prioritise your top 20 by traffic or revenue first — those pages drive the majority of cross-sell opportunity.
Theme Block and Display Requirements
For complementary product recommendations to reach shoppers, your theme must include a dedicated Complementary products block in the Product page template — configuring the Search & Discovery app alone is not sufficient. This two-step requirement is the most common reason SA merchants configure the app and then see nothing change on their storefront.
How to check and activate the block:
- Go to Online Store → Themes → Customize.
- Navigate to the Product page template.
- In the left panel, click Add block.
- Look for "Complementary products" in the list. If it's there, add it and position it near the top of the product information section — close to the add-to-cart button, not buried below the description.
- Inside the block settings, find the Maximum products to show field. Shopify's guidance for theme developers recommends defaulting to 2–3 visible items, with pagination for any remaining assigned recommendations.
- If the block doesn't appear in the Add block list, your theme doesn't include it natively.
Common mistake: Completing the Search & Discovery setup, then assuming recommendations are live. If your theme doesn't have the block, or you haven't added it in the theme editor, shoppers see no suggestions from the app — the configuration and the theme display are two independent steps.
Not all free Shopify themes include the complementary products block out of the box. Premium themes (Impulse, Prestige, Warehouse and others available in the Shopify Theme Store) are more likely to include it natively. If your theme doesn't support it and editing theme code isn't an option, a page-builder app like a custom Liquid block or a dedicated cross-sell app is the cleaner route.
Is your theme blocking the cross-sell block?
Send us your store URL and we'll check theme compatibility and show you exactly where to add the complementary products block — or recommend the lightest fix if the theme doesn't support it natively.
Native App vs Paid App: Decision Table for SA Merchants
The free Search & Discovery app handles the standard cross-sell use case well. A paid app makes sense when you need capabilities the native tool deliberately omits.
| Your situation | Native app sufficient? | Consider paid app? |
|---|---|---|
| Fewer than ~100 active products | ✓ Yes — manual setup is manageable | Not needed |
| Need click and revenue attribution per recommendation | ✗ No built-in recommendation analytics (practitioner-documented) | ✓ Yes |
| Want to test different pairings (A/B) | ✗ Not supported | ✓ Yes |
| Need bundle discount for the pairing | ✗ No discount attachment | ✓ Yes |
| Large catalog (500+ products) needing auto-pairing | ✗ Manual only — not scalable | ✓ Yes |
| Premium theme with native block support | ✓ Install app + activate block | Not needed for display |
| Free theme without native block | Needs code edit to add block | ✓ Paid app may be simpler |
| Highly variable stock (items go in/out frequently) | ⚠ Pairings go blank when stock hits 0 | ✓ Paid apps offer fallback logic |
The native app's biggest omission for most growing SA stores — according to multiple practitioner guides — is the absence of a dedicated analytics dashboard: no click tracking, no revenue attribution per recommendation, no conversion data per pairing. Shopify's own documentation for the Search & Discovery app does not describe built-in recommendation reporting; if this matters for your store's decision, verify the current app listing at apps.shopify.com/search-and-discovery. If you're investing time in manual pairings, a paid app with attribution pays for itself quickly once your store reaches meaningful order volumes.
Decision rule of thumb
Start with the free Search & Discovery app if you have under 100 products and a premium theme. Graduate to a paid cross-sell app when you need to know whether the feature is actually generating revenue — no analytics means you're optimising blind.
Pairing Logic for SA Shopify Stores
Effective shopify complementary products pair items that solve an adjacent problem the shopper hasn't thought of yet, rather than items that are simply sold in the same category.
Three pairing models that work consistently across SA product categories:
- Consumable + product. A skincare serum paired with a matching cleanser. A printer cartridge with a ream of paper. The consumable has a shorter replenishment cycle, so the cross-sell starts a second purchase before the customer has left the first one.
- Accessory + hero item. A phone case paired with a screen protector. A pair of sneakers paired with branded socks and a shoe-cleaning kit. Accessories have lower price points than the hero item, making the add-to-cart decision feel small relative to what the shopper has already committed to.
- Service upgrade + product. Extended warranty, installation service, or gift wrapping shown alongside the main item. Common in electronics and furniture segments, where SA shoppers often want peace of mind on higher-value purchases.
SA-specific consideration: Two-thirds of SA shoppers cite free delivery as the primary reason they complete a purchase, according to consumer research. When a shopper's cart sits just below your free delivery threshold, a lower-priced complementary suggestion appears as both a useful add-on and a route to clearing that bar. Positioning the block with copy like "Add to qualify for free delivery" compounds its conversion value — provided the threshold is visibly stated elsewhere on the page.
One caution: avoid pairing items priced higher than the product being viewed. A high-priced add-on suggestion shifts the decision from a quick cross-sell to a fresh purchase consideration — and often results in neither item being added. Keep Shopify complementary recommendations priced at equal to or below the main product; the lower the add-on price relative to the hero item, the more impulsive the decision to add it.
For the more technically configured stores using Shopify Metafields, you can also use metafields to pass complementary product data to custom theme sections — useful if you want the recommendations block to appear in a non-standard location (inside a tab, for instance) without relying on the standard block position.
Why South African Businesses Choose Growth Pulse Media
Getting the Search & Discovery app installed is the easy part. The harder question is whether your cross-sell strategy is built around your actual margin mix, stock patterns, and checkout flow — or whether it's generic configuration that sits untouched after launch.
Growth Pulse Media approaches Shopify as an operator, not a configuration technician. Dirk van Greuning built and scaled a South African ecommerce business before founding the agency — that background means cross-sell recommendations get evaluated against real unit economics: margin on the paired item, stock velocity, and whether pushing the shopper toward a lower-margin add-on actually improves the order's contribution before courier costs.
If you're looking for a Shopify marketing agency in South Africa that will audit your entire conversion stack — product page structure, recommendation logic, checkout flow, and post-purchase email — rather than implement features in isolation, that is specifically what we do. We carry a limited client load so each store gets senior attention, and all work is executed in-house.
Who This Is NOT For
Dropshippers with no catalog control. If you're dropshipping and don't control which items are in stock week to week, complementary product recommendations will constantly go blank as supplier inventory fluctuates. The feature requires a reasonably stable catalog to be worth the setup time.
Single-product stores. If you sell one item — or a very narrow range with no natural add-ons — there's nothing meaningful to pair. Related product sections are also thin. Invest the same time in checkout optimisation instead.
Merchants who want automated recommendations without curation. The native Shopify Search & Discovery app requires you to manually assign pairings for every product. If you want machine-learning-driven cross-sell suggestions based on actual purchase behaviour, you need a paid app or a custom Shopify Storefront API integration. The free tool doesn't do this.
Stores on themes without a complementary products block and no developer access. If your theme doesn't include the block and you can't edit Liquid code or hire someone who can, the feature requires a workaround. Consider a paid page-builder or cross-sell app that doesn't depend on the native theme block.
Want an honest assessment of whether this feature will move the needle for your store?
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Frequently Asked Questions
What is the difference between complementary products and related products in Shopify?
Complementary products are items shoppers buy alongside a product — they're cross-sell suggestions meant to increase the same order's value. Related products are alternatives in the same category that help shoppers compare before deciding. In Shopify, related products can be auto-generated by the platform; complementary products must be manually assigned through the Search & Discovery app. Complementary items also hide automatically when they go out of stock, while related products can still display with the "continue selling" setting enabled.
Does setting up Shopify complementary products cost anything?
The Shopify Search & Discovery app used to configure Shopify complementary products is free on all Shopify plans. There is no additional monthly fee. The cost consideration arises if your theme doesn't include a native complementary products block and you need a developer to add one, or if you upgrade to a paid cross-sell app for analytics and automation features the native tool lacks.
How many complementary products can I add per listing?
Shopify allows up to 10 complementary products per listing through the Search & Discovery app. As a practical working guideline, assigning 4–6 pairings per product gives the block enough options to display even when one or two items go out of stock, since out-of-stock items are automatically excluded from the display.
Why aren't my complementary products showing on my store?
The two most common reasons are: the Search & Discovery app is configured but the Complementary products block hasn't been added to the theme editor, or one or more of the recommended items is out of stock. Check the theme editor under the Product page template and confirm the block exists and is positioned correctly. Also verify that the items you've assigned are in stock — the feature hides recommendations automatically when stock hits zero.
Can I use complementary products to offer a discount for buying together?
Not through the native Shopify Search & Discovery app. The native tool surfaces recommendations but cannot attach a bundle discount to the pairing. If you want a "buy together and save" mechanic alongside the cross-sell suggestions, you'll need a paid app like Frequently Bought Together or a similar tool from the Shopify App Store, combined with a Shopify discount code or automatic discount configured separately.
Ready to turn your product pages into higher-value carts?
Growth Pulse Media configures Shopify cross-sell recommendations as part of a broader conversion audit — checking your theme compatibility, pairing strategy, stock logic, and checkout flow in one pass. As a registered Shopify Partner, we implement natively and don't layer on unnecessary paid apps. No obligation — we'll get back to you within 24 hours.
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