Kelso Tool WorksShopify App Catalog No. 01No revenue share. No overage fees.
Kelso
Back in Stock Alerts · Part No. BIS-001

Restock alerts that never miss.

A back in stock app for Shopify built like a tool, not a toy. Two-path restock detection. Paced sends. A full audit log. Flat pricing from $0.

Launching on the Shopify App Store this month. Early installs get free white-glove migration from your current app.

01 · How detection worksDWG BIS-001-A

Two paths. Zero misses.

Shopify does not guarantee webhook delivery. After 8 failed retries, it deletes the subscription entirely. Apps that rely on webhooks alone drift out of sync and send alerts for stock that is not there, or send nothing at all.

Kelso runs the webhook for speed and a scheduled reconciliation poll for certainty. If the webhook drops, the poll catches the restock within minutes. Your subscribers still get their email.

SHOPIFYINVENTORYAKELSOQUEUEBSENDENGINECWEBHOOKINSTANTRECONCILIATION POLLEVERY 15 MIN · CATCHES DROPPED WEBHOOKSPACEDBATCHESAUDIT LOGEVERY SEND ACCOUNTED FORFIG. 01 · RESTOCK DETECTION · DWG BIS-001-ATWO PATHS. ZERO MISSES.
02 · Feature specSPEC SHEET BIS-100
BIS-101

Storefront widget

THEME BLOCK + SNIPPET

A "Notify me" button that matches your theme. Ships as an OS 2.0 theme app block, with a snippet fallback for legacy themes. Copy and colors are yours to set. Product page in v1, collection page next.

BIS-102

Variant-level matching

EXACT SIZE + COLOR

Subscribers sign up for the exact variant they want. When the medium in green comes back, only the people waiting for the medium in green hear about it. Multi-location aware where Shopify provides the data.

BIS-103

Send engine + audit trail

QUEUED, PACED, LOGGED

Sends go out in paced batches through a warmed sending domain, not one giant blast. You control batch size and pacing. Every alert is logged: queued, sent, delivered, clicked. If you can ask about it, we can account for it.

BIS-104

Restock detection

WEBHOOK + POLL

The inventory webhook triggers instantly. A scheduled reconciliation poll runs behind it and catches anything Shopify drops. Two paths, so one failure never means a missed restock.

BIS-105

Klaviyo integration

EVENTS IN, YOUR FLOWS

Kelso fires subscribe and restock events into Klaviyo. Run our widget and detection with your Klaviyo flows doing the sending, or let Kelso send. Mailchimp and Omnisend are supported too.

BIS-106

Migration import

CSV, ONE UPLOAD

Leaving another app? Export your waitlist as a CSV and upload it. Subscribers, products, and variants carry over. Your waitlist survives the switch.

BIS-107

Compliance

EU DOUBLE OPT-IN

Single opt-in by default. Double opt-in is a toggle, switched on automatically for EU storefronts. Shopify GDPR webhooks are handled: data requests, customer redaction, shop redaction.

BIS-108

Demand analytics

WAITLIST → REVENUE

A dashboard of your most-waitlisted products and variants, sent, opened, and clicked counts, and recovered revenue. Know what to restock before you restock it.

03 · Price listLIST BIS-2026
Ref.PlanMonthlyAnnual (~20% off)Sends/moIncluded
PLAN-00Free$0n/a50Unlimited subscribers and variants. 1 ESP integration.
PLAN-01Starter$14/mo$134/yr750All integrations. Double opt-in. Batch-send control.
PLAN-02GrowthMOST STORES PICK THIS$29/mo$278/yr3,000Multi-location. Priority support.
PLAN-03Scale$59/mo$566/yr10,000Dedicated sending reputation. Priority support.

Every plan: unlimited subscriber capture, variant-level matching, full send audit log. No revenue share. No per-unit fees. No overage charges. Over your limit, sends hold until you upgrade or the month resets. Annual is roughly 20% off.

Not sure which plan fits? The pricing page has a calculator. Two numbers in, a plan out.

04 · QuestionsFAQ BIS-900
How long does setup take?

Install the app, add the widget block in your theme editor, and you are live. Most stores finish in under 5 minutes. Legacy themes use a paste-in snippet, which adds a few minutes.

Will it work with my theme?

Yes. On OS 2.0 themes the widget is a native app block you place in the theme editor. On older legacy themes we provide a snippet fallback, so the widget renders either way. If it does not look right, email us and a person will fix it with you.

What happens if I go over my send limit?

Sends hold. They are never dropped. Alerts queue up, we notify you, and the queue releases when you upgrade or when your month resets. You never lose a subscriber or an alert to a limit.

Do you support double opt-in for EU customers?

Yes. Double opt-in is a toggle on paid plans, and it defaults to on for EU storefronts. Subscribers confirm by email before they are added to the waitlist.

Can I migrate from Appikon, Swym, Amp, or another app?

Yes. Export your waitlist from your current app as a CSV and upload it in Kelso. Subscribers and their variant selections carry over. If your old app has no export, email support and we will help you find a path.

Does it work with Klaviyo?

Yes. Kelso fires subscribe and restock events into Klaviyo, so you can use your own Klaviyo flows for sending while Kelso runs the widget and restock detection. Mailchimp and Omnisend integrations are included too.

Do you charge a revenue share or overage fees?

No. Flat monthly price for a send allowance. No revenue share, no per-unit fees, no surprise charges at the end of the month. The pricing table above is the whole deal.

What happens to my waitlist if I downgrade or cancel?

Subscriber capture is unlimited on every plan, including Free, so downgrading never deletes your waitlist. Only send volume is gated. If you uninstall, your data is deleted per our privacy policy and Shopify GDPR webhooks.

Stop losing restocks.

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