Here’s a short, practical list of well-reviewed Shopify apps for upselling and cross‑selling (with what each one is best at so you can pick fast).

Top picks

• One Click Upsell — Zipify OCU

  • Best for: high‑volume stores and Shopify Plus merchants that want full funnel (pre‑ and post‑checkout) upsell funnels and A/B testing.
  • Key features: pre-purchase & post‑purchase funnels, cart drawer upsells, Shop App integration, analytics; performance-oriented pricing options. (apps.shopify.com, zipify.com)

• ReConvert — Upsell & Cross Sell

  • Best for: stores that want a powerful thank‑you / order‑status page builder and easy one‑click post‑purchase funnels.
  • Key features: drag‑and‑drop thank‑you page builder, one‑click upsells, segmentation & A/B testing, built for quick setup. (reconvert.io, apps.shopify.com)

• Rebuy (Personalization Engine)

  • Best for: merchants who want AI/personalization across product recommendations, cart, checkout and post‑purchase with deeper customization.
  • Key features: AI recommendations, Smart Cart™, post‑purchase monetization, modular packages for cart/checkout/search/flows. (apps.shopify.com)

• Frequently Bought Together — Code Black Belt

  • Best for: Amazon‑style “frequently bought together” bundles and simple add‑on conversions.
  • Key features: AI recommendations trained on order history, bundle discounts, multiple placement options and review integrations. (apps.shopify.com, web.codeblackbelt.com)

• Candy Rack — All‑in‑One Upsell

  • Best for: stores that need lightweight, fast embedded offers across product, cart and post‑purchase with simple pricing tiers.
  • Key features: embedded one‑click offers, AI mode, fast load times, per‑orders pricing tiers. (apps.shopify.com)

• PickyStory (Bundles)

  • Best for: merchants who sell outfits/kits or want “bundle as a single product”, mix‑and‑match, and shoppable lookbooks.
  • Key features: mix & match bundles, buy‑X‑get‑Y, lookbooks, gallery/collection placements. (pickystory.com, gptmediabuyer.com)

• LimeSpot Personalizer

  • Best for: merchants looking for AI‑driven recommendations and merchandising (personalized widgets, post‑purchase offers, A/B testing).
  • Key features: recommendation boxes, cart/checkout upsells, personalized product pages, analytics. (limespot.com, shopdigest.com)

Other lightweight / budget options to consider

• Selleasy (Upsell & Cross Sell) — low starting price and order‑based tiers; good for simple product/cart upsells. (amasty.com, aureatelabs.com)

How to choose (quick checklist)

• Where do you want the upsell? (product page, cart, checkout, thank‑you page, or post‑purchase) — some apps (Zipify, ReConvert, Rebuy) cover multiple stages; others focus on product/cart or thank‑you only. (apps.shopify.com, reconvert.io)
• Shopify plan: if you need native checkout extensions (in‑checkout or true post‑purchase) check Shopify Plus compatibility. Zipify and LimeSpot / Rebuy call out Plus support. (zipify.com, limespot.com, apps.shopify.com)
• Test with the free trial and A/B test offers — conversion impact varies by store and product mix (all listed apps offer trials or free tiers). (apps.shopify.com, reconvert.io)

If you want, I can:

• Narrow this to the 2–3 best apps for your exact use case (e.g., “post‑purchase only”, “bundles & kits”, or “small budget store”), or
• Compare 2 specific apps side‑by‑side (features, pricing, Plus compatibility, pros/cons).

Which scenario matches you: post‑purchase funnels, product bundles/kits, cart widgets, or full personalization?