Here’s a compact, action-oriented list of the top types of tools that reliably boost average order value (AOV) in e‑commerce — with best‑in‑class examples and a one‑line reason to use each. I’ve grouped by tactic so you can pick quick wins vs longer‑term investments.

Quick wins (low lift, fast AOV upside)

• Post‑purchase / one‑click upsells: Zipify OneClickUpsell (OCU), ReConvert. Let customers add high‑margin items after they buy (no extra acquisition cost). (apps.shopify.com)
• “Frequently bought together” / one‑click bundles: Frequently Bought Together (Code Black Belt), BST/Beast Bundles, PickyStory. Amazon‑style pairings + one‑click add = immediate unit lift. (apps.shopify.com)
• Free‑shipping progress bar / threshold nudges: Hextom Free Shipping Bar, OptiMonk announcement bars. Showing “$X away from free shipping” pushes shoppers to add items. (owlmix.com, optimonk.com)

Personalization & mid‑term levers (medium lift, scalable)

• Product recommendations & personalization engines: Nosto, Searchspring, Algolia (site search + recommendations). Personalization + cart recommendations reliably raise AOV. (Nosto case studies show double‑digit AOV lifts in multiple examples.) (nosto.com, searchspring.com)
• Email + SMS data‑driven automation: Klaviyo. Use post‑purchase flows, cross‑sell sequences and segmented product recs to lift order sizes and repeat value (case: Made In saw ~26% AOV growth after consolidating flows). (businesswire.com, klaviyo.com)
• Loyalty & VIP programs: Smile.io / Loyalty platforms. Reward points, VIP tiers and redemption options raise frequency and AOV among members (case examples show big lifts in loyalty‑member AOV). (resources.smile.io, learn.smile.io)

Payment, discovery & optimization (strategic investments)

• Buy‑Now‑Pay‑Later (BNPL): Klarna / Afterpay / Affirm. Offering BNPL often increases cart size and conversion (merchants report meaningful AOV uplifts when BNPL is shown at checkout). (businessinsider.com, quickmarketpitch.com)
• Search & product discovery (to surface higher‑value items): Searchspring, Algolia — better search + predictive bundling finds complementary items and raises AOV. (searchspring.com, algolia.com)
• Experimentation & CRO platforms: VWO, Optimizely, Hotjar (behavior insights + A/B testing). Test different upsell placements, threshold levels, bundles and CTAs to measure real AOV impact. (vwo.com, hotjar.com)

How to pick and roll out (practical checklist)

1. Quick audit: find the top 3 pages where shoppers drop (product page, cart, thank‑you).
2. Quick wins first: add a free‑shipping bar + “frequently bought together” widget + a simple post‑purchase upsell. (Low cost, fast ROI.) (owlmix.com, apps.shopify.com)
3. Measure & A/B test: implement one change at a time and track AOV, attach rates and return on ad spend (use VWO/Optimizely/GA+Hotjar). (vwo.com, hotjar.com)
4. Scale with personalization: add a recommendation engine (Nosto/Searchspring) and feed it your sales + behavioral data for dynamic bundles and post‑purchase offers. (nosto.com, searchspring.com)
5. Retain & increase LTV: layer email/SMS flows (Klaviyo) and a loyalty program (Smile.io) to turn higher AOV into higher lifetime value. (klaviyo.com, resources.smile.io)

Five straight‑to‑the‑point evidence points (helpful for vendor conversations)

• Zipify OneClickUpsell is a top choice for one‑click post‑purchase funnels on Shopify. (apps.shopify.com)
• Made In reported ~26% AOV growth after consolidating email/SMS and reviews in Klaviyo. (klaviyo.com)
• Nosto’s post‑purchase and recommendation products have driven large AOV uplifts for early adopters (examples cited include +58% where offers were accepted and other double‑digit AOV gains). (prweb.com, nosto.com)
• Smile.io loyalty programs have produced big loyalty‑driven revenue/AOV lifts in case studies (e.g., Death Wish Coffee saw large increases in loyalty‑generated revenue and AOV among members). (resources.smile.io)
• BNPL options (Klarna/Affirm/Afterpay) are widely reported to increase cart size and conversion when offered at checkout. (businessinsider.com, quickmarketpitch.com)

If you want, I can:

• Recommend the best 2–3 specific apps for your platform (Shopify / BigCommerce / WooCommerce) and budget, or
• Draft a 30‑90 day rollout plan (which items to A/B test first and what KPIs to watch).

Which would you prefer?