Prevent Shopify overselling with real cart reservations.
Cart Reserve holds stock when shoppers add items to cart, displays a checkout countdown timer, and validates each reservation through purchase. Expired carts release inventory automatically.
Free plan available · 5-minute setup · paid plans include a 14-day trial
5.0rated by Shopify merchantsThat unit is reserved instantly. No one else can take it.
On Pro and Max, AI scores each cart-add in <200ms. Suspicious sessions never reach stock.
Abandoned carts return stock on their own. No cleanup.
Without Cart Reserve
What one oversold drop actually costs you.
In the box
Everything in the box. Nothing you don't need.
Six capabilities, active by default. No plugins, no SDK.
Built for sneakers · watches · streetwear · supplements · collectibles · premium pre-orders — any Shopify store running drops.
Security
Fans get the product. Not bots.
Four quiet layers work in the background — so reservations stay fair, checkout stays clean, and the calls about phantom orders stop coming.
We spot a real customer before they even reach checkout — hundreds of signals from mouse movement to browser behaviour. Suspicious sessions get blocked, borderline ones land in your queue.
Shopify inventory reservation
How Cart Reserve prevents overselling
Cart Reserve is a Shopify stock reservation app. It holds eligible inventory when a shopper adds an item to cart, keeps the reservation attached to that cart, and releases the stock when the hold expires or checkout completes.
- 01Reserve stock at add to cart
- 02Validate reserved items at checkout
Cart timer, cart lock, or real inventory hold?
- 03Release expired carts automatically
- 04Control cart hoarding during product drops
Built for limited-stock Shopify stores: handmade restocks, one-of-one products, collectibles, sneakers, streetwear, flash sales, and high-demand product drops.
Pricing
Start free. Scale when your drops do.
Use the Free plan for as long as you need. Paid plans include a 14-day trial.
- Unlimited reservations
- 25 concurrent active holds
- 3 protected products
- Fixed 10-minute timer
- 1-day analytics history
- Unlimited reservations
- 100 concurrent active holds
- 100 protected products
- Configurable 5–60 minute timer
- Fair queue during high-traffic drops
- 7-day analytics history
- Unlimited reservations
- 500 concurrent active holds
- 500 protected products · advanced fair queue
- AI-powered fraud detection
- Full storefront customization
- 30-day session and analytics history
- Unlimited reservations
- 2,500 concurrent active holds
- Unlimited protected products · ALL mode
- Auto-protect new products · global inventory limits
- Unlimited IP & country blocking
- 90-day analytics history · priority setup support
Free plan available · 14-day paid-plan trial · Start at $0. Paid plans are billed through Shopify after the trial.
The founders
We're three engineer brothers in Brno. We built Cart Reserve to help Shopify merchants stop overselling and protect every drop.
The R3Stack brothers · Brno, Czechia
FAQ
Questions
Does it slow down my store?
No — checks run server-side in under 200ms. No impact on Core Web Vitals.
What if a shopper doesn't check out?
Free uses a fixed 10-minute hold. Paid plans let you choose 5–60 minutes. Stock auto-releases when the hold expires.
Will it block real customers?
Under 0.1% false positive rate in beta. Sensitivity is adjustable per product.
How long does setup take?
About 5 minutes. Install from the Shopify App Store, configure your hold timers, done. No code changes to your theme.
Free trial?
Paid plans include a 14-day trial with that plan's features. Free has no time limit.
How do I prevent overselling on Shopify?
Cart Reserve creates a stock reservation when an eligible item enters the cart, moves held units from Shopify's available state to reserved, and releases them on expiry. Checkout validation rejects protected quantities without a valid reservation.
Can Shopify reserve stock when a customer adds it to cart?
Cart Reserve adds this behavior for tracked products with finite stock. It creates a timed inventory hold at add to cart, shows a countdown timer, and returns the stock automatically if the shopper does not complete checkout.
Is a checkout timer the same as an inventory reservation?
No. A timer is only a visual countdown. Cart Reserve pairs the timer with a server-side stock reservation and Shopify checkout validation so the held units stay protected through purchase.
How does Cart Reserve prevent cart hoarding and bots?
Product quantity limits and concurrent-hold capacity restrict how much scarce stock one cart can lock. Starter adds rule-based bot protection, Pro and Max add AI detection, and Max adds IP and country blocklists.
Does Cart Reserve work for product drops and flash sales?
Yes. Cart Reserve is designed for limited-stock launches, handmade restocks, one-of-one items, flash sales, and product drops. Fair queueing controls traffic spikes while active shoppers keep a timed claim on inventory.
Your next drop doesn't have to end in refunds.
Install Cart Reserve before your next launch. It takes 5 minutes.
Free plan available · Paid plans include a 14-day trial · Billed through Shopify