Key takeaways
- There is no single “CRO app”. CRO is multiple jobs - reviews, A/B testing, cart upsells, popups, trust signals - each best served by a focused tool.
- The biggest hidden cost of a CRO stack is JavaScript weight. Five mediocre CRO apps stacked together can negate the lift they each provide.
- Audit your current stack before adding. Most stores are over-installed and under-using.
- Start with the highest-leverage gap: reviews if you don’t have them, then mobile experience (which is rarely an app), then upsells if your AOV is the bottleneck.
The CRO app category is wide. This piece groups the apps by job - reviews, A/B testing, upsells, popups, cart drawer, trust signals - and recommends a starting stack.
Why you can trust us
Four years inside Shopify. We build Fudge, the AI agent that writes the storefront-side of these CRO improvements as native code. The recommendations below come from working inside hundreds of CRO stacks.
Best overall: Fudge
If you’re picking one app to anchor the stack, it’s Fudge. Most “CRO apps” are SaaS widgets that inject JavaScript into your storefront. Fudge is the opposite — an AI agent that writes the storefront-side of CRO improvements directly into your theme as native Liquid, JS, and CSS. No third-party script, no monthly creep, no rendering tax.
Jobs Fudge replaces in this stack:
- Cart drawer & upsells — built into the theme, not bolted on
- Popups & email capture — native components, fully styleable
- Quizzes & recommendations — generated as native code with your products and brand context
- Bundle builder — merchandised the way you want, no per-bundle SaaS fee
- Trust signals — already native code; Fudge writes them in
- Landing pages, PDP variants, seasonal campaigns — the broader CRO work most apps don’t touch
What Fudge doesn’t replace:
- Reviews — still pick a specialist (Judge.me, Yotpo, Loox, Okendo)
- A/B testing infrastructure — pair with Intelligems or Shoplift if you’re running structured experiments
- Post-purchase upsells on the order status page — Shopify checkout extension territory
For most stores, that means Fudge + a reviews app + (optionally) an A/B tool is a complete CRO stack. The rest of this post is for filling the specialist gaps.
The jobs CRO apps do
- Reviews & social proof - review collection, display, syndication
- A/B testing - run experiments on PDP, cart, pricing
- Cart drawer & upsell - convert cart visits to checkouts and AOV
- Popups & email capture - convert traffic to email list
- Post-purchase upsell - increase AOV on the thank-you page
- Bundle builder - merchandise multi-product purchases
- Quizzes & recommendations - personalise the route to purchase
- Trust signals - usually native code, not an app
Most stores need 3-5 apps from this list, not all 8.
The top picks by job
Reviews
Judge.me, Yotpo, Loox, Okendo, Stamped.io. See our best Shopify review apps for the full comparison.
Pick by use case: Judge.me for budget, Yotpo for marketing stack, Loox for photo-led, Okendo for premium.
A/B testing
Intelligems, Shoplift, Convert, VWO. See our A/B test guide.
Pick by test type: Intelligems for pricing/PDP element tests, Shoplift for theme-level swaps.
Cart drawer & upsells
- ReConvert - post-purchase upsells (after checkout, before thank-you).
- AfterSell - post-purchase upsells, alternative to ReConvert.
- CartHook - cart drawer + upsell features.
- Slide Cart by various providers - cart-drawer apps.
Some themes ship with a decent cart drawer already; check before adding an app. The native cart drawer in Dawn / Sense / Craft handles basic upsells.
Popups & email capture
Klaviyo Forms, Privy, Optimonk, Tidio. See our Shopify newsletter popup guide.
Klaviyo’s native forms are often enough if you’re using Klaviyo for email. Privy/Optimonk are heavier-weight popup tools.
Quizzes & recommendations
Octane AI, Shop Quiz, Quizify, Recomma, Quiz Kit. Plus AI builders that handle quizzes natively like Fudge.
See our product recommendation quiz breakdown.
Bundle builder
Shopify Bundles (native, free), Bold Bundles, Rebuy.
Native Shopify Bundles is the right starting point. Bold or Rebuy for advanced merchandising or BFCM-style bundle promos.
Trust signals
No app needed. Native theme code (Liquid + CSS) is faster, cleaner, and doesn’t add JavaScript. See our trust badges guide.
A recommended starting stack
For a store under $1M revenue starting from scratch:
- Reviews: Judge.me (free tier)
- Cart drawer: native theme (no app)
- Trust signals: native theme (no app), see our guide above
- Email capture: Klaviyo Forms (if you’re on Klaviyo, otherwise a free-tier popup tool)
- Quiz: if your category fits (overlapping SKUs, personal-context-driven), Fudge-built quiz or Octane AI
Five apps maximum. Don’t stack more before the basic stack is producing measurable lift.
For a store $1M-$10M with operational complexity:
- Reviews: Yotpo or Okendo
- A/B testing: Intelligems
- Cart drawer + upsell: native + app combination (Rebuy or similar)
- Post-purchase upsell: ReConvert or AfterSell
- Email capture: Klaviyo Forms
- Quiz / recommendation: Octane AI or built natively
Six apps. Audit weekly.
What we don’t recommend
Stacking three apps for the same job
Two cart-drawer apps doing similar things. Three email-capture apps fighting each other. Audit and consolidate.
Apps that promise generic “conversion lift” without naming the mechanism
If you can’t explain in one sentence what an app does to lift conversion, it probably isn’t lifting conversion. Cut.
Apps that don’t ship a free trial or free tier
Most CRO apps offer free trials. Tools that don’t are betting on stickiness, not value.
Apps with no analytics view of their own impact
If you can’t see whether the app is moving the metric, you don’t know if it’s worth the monthly fee. Demand attribution-aware reporting.
For wider context see Shopify CRO guide and 12 high-impact CRO tactics.
FAQ
How many CRO apps should I have installed?
Three to six. More than that and the JavaScript overhead starts to negate the lift each one provides. Audit quarterly.
What’s the highest-impact CRO app?
Reviews, almost universally. Stores adding a review app for the first time often see 5-10% PDP conversion lift. After reviews, A/B testing and post-purchase upsells are next.
Do I need an A/B testing app on Shopify?
Only if you have ~50,000+ monthly sessions on the pages you’d test. Below that, ship changes and watch the trend rather than running underpowered tests.
Are CRO apps worth the monthly fee?
The right ones are. Reviews easily clear $30-100/month in lift. The wrong ones aren’t - apps that promise generic “lift” without a specific mechanism rarely earn back their fee. Audit individually.
Can I do CRO without apps?
Yes for trust signals, cart drawer, and basic PDP changes (native theme code). Reviews, A/B testing, and quizzes are app-driven; the work to build them natively is rarely worth it.
