The back-in-stock app for Shopify. Tell them when it's back.
Slingshot is a back-in-stock app for Shopify. It collects email and phone signups when products run out, sends alerts the moment they restock, and ties every alert to the sale it earned. Free up to 100 alerts a month.
Free plan • No credit card required • Live in 5 minutes
Your sold-out products are still earning. For someone else.
Customers who can't buy from you today buy from your competitor tomorrow. Slingshot brings them back the moment you restock.
Reach them where they actually open it.
Email. SMS. Widget on your store. Pick one, pick all three.
Six on-brand templates (Bold, Classic, Commerce, Editorial, Essential, Modern). Custom-from domain on Pro with DKIM. Business address auto-injected for CAN-SPAM and GDPR.
Flex SMS
Pay only for what you send: $0.015 per SMS, US/CA only, capped so a viral product can't bankrupt you. Opt-in approval flow keeps deliverability clean.
On-site signup widget
An embeddable widget that appears the moment a product is out of stock. Style it to match your theme's fonts, colors, and buttons so it looks native, not bolted on. One click to subscribe, no code required.
By the numbers
Back-in-stock alerts are the highest-ROI email a Shopify store can send.
Industry benchmarks from across email and SMS back-in-stock programs.
- 8 to 12%
- Typical recovery rate when alerts go out within 24 hours of restock.
- Industry benchmark across email and SMS
- 70%+
- Average open rate on back-in-stock emails — among the highest of any transactional email type.
- Across major email service providers
- 5 minutes
- Average time to install Slingshot and start collecting your first signups.
- Slingshot internal data
What are your stockouts costing you?
Plug in your numbers. See what you're losing, and what Slingshot can bring back.
Your typical AOV in USD
Distinct out-of-stock events across all variants
How many shoppers want each restocked item, on average
Industry benchmark is 8-12%
$2,250
Estimate only. Recovery rate depends on your category, audience, and how fast you restock.
Install at 2pm. Collecting signups by 2:05.
Install, customize, ship. No code required.
Connect Shopify
Install from the App Store. We sync your products and inventory automatically.
2 minsCustomize alerts
Pick a template, match your brand colors and voice. Add SMS if you want.
5 minsGet the sale
The moment a product restocks, we notify the customers waiting for it. You see which alerts earned which sale.
Always-onSimple, transparent pricing.
Three plans. No contracts. SMS only when you turn it on.
Free
Try it on your first 100 alerts a month.
- 100 notifications/month
- 1 customer locale
- Email notifications
- All 6 templates
- Basic revenue tracking
Starter
For stores doing 100–1,000 orders a month.
- 1,000 notifications/month
- 3 customer locales
- Email + on-site widget
- Custom branding & templates
- Advanced revenue tracking
- Email overage at $0.01 (capped at $30/mo)
Pro
For high-volume stores with 1,000+ orders per month.
- 10,000 notifications/month
- Unlimited customer locales
- Email + Flex SMS + on-site widget
- Custom-from email domain (DKIM)
- Advanced revenue tracking
- Flex SMS at $0.015 (US/CA only, $300/mo cap)
Why we're different
Klaviyo sells a marketing suite. We sell a back-in-stock app. That's the whole pitch.
— Thomas, Slingshot
One thing, done well.
Klaviyo gives you a marketing suite. Slingshot gives you a back-in-stock app. And tells you which alerts earned which sale.
| Feature | Slingshot | Klaviyo Email |
|---|---|---|
| Back-in-stock alerts | Yes | gated to Email plan |
| Revenue attribution per alert | Built-in | Manual reporting |
| Email + SMS + on-site widget | Yes | bundled with full CRM |
| Custom-from email domain (DKIM) | Pro plan | Yes |
| 6 templates included | Yes | Yes |
| Pay only for back-in-stock | Yes | Bundled with marketing |
| Starting price (10k contacts equiv.) | $59/mo | $200+/mo |
Comparison based on Klaviyo Email tier with ~10k contacts. Slingshot Starter from $19/mo. Flex SMS is pay-as-you-go at $0.015/msg, US/CA only.
Frequently asked questions
If something's missing, write to thomas@heyslingshot.com.
From the desk of
Friends running Shopify stores were paying $300 a month to send one email. So I built the smaller, sharper version.
Stop losing sold-out shoppers to the next tab.
Your first 100 alerts a month are free. The next stockout pays for the rest.