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Back-in-stock alerts on WhatsApp: waitlists and restock broadcasts

By DilKart Editorial. Updated 16 October 2026.

A sold-out product is a list of people who already said yes. When it comes back, the fastest way to turn them into orders is a WhatsApp message, because it gets read within minutes and the buyer can tap straight through.

This guide covers building the waitlist, sending the restock message, and doing it at the right cost. With Tadlo AI, restock, winback and review messages are sent as opted-in broadcasts from the Growth plan, with the cost shown before you send. We did not find scheduled or event-triggered restock, winback, review or reorder automations in its published plans, so you choose the segment and send each broadcast yourself.

Building the waitlist

  1. Add a "Notify me on WhatsApp" button on sold-out product pages.
  2. Collect the phone number with clear opt-in wording that names your store and the product.
  3. Tag each contact with the product and size they want.
  4. On Instagram, a RESTOCK keyword can collect interest and send people to the same opt-in.
  5. Keep the list per product, not one big list.

Opt-in wording

"Message me on WhatsApp when this is back in stock. [Store] may also send offers; reply STOP to opt out." Meta requires businesses to collect opt-in that clearly states the person is agreeing to receive messages from the business, and names the business. If you only promise a restock alert, send only the restock alert.

Sending the restock broadcast

  1. When stock arrives, update the product page first.
  2. Select the segment: people waiting for that product and size.
  3. Check the cost preview before sending.
  4. Send the approved template with the product link.
  5. Watch replies; some will ask about other sizes.

Template category and cost

A restock alert is promotional, so Meta classes it as marketing: ₹0.8631 per message to Indian numbers from 1 October 2026. A list of 500 waiting buyers costs about the same as a small ad, and it reaches people who already asked for the product.

Stock smaller than the list?

If you restock 50 units and 500 people are waiting, say so honestly: "Limited units back today." Consider sending in batches, starting with the earliest sign-ups, so you do not disappoint hundreds of people in one go.

Timing

After the restock

Remove people who bought from the waiting segment, so they never get a second alert for something they already own. Keep the others for the next restock, or let the list expire after a set time and say so in the opt-in.

Restock alerts from Instagram

Sold-out products get "restock?" comments on Instagram. Reply with a DM that invites them to the WhatsApp waitlist, since Instagram limits messages to 24 hours after their last message and cannot reach them on restock day.

Measure

Track waitlist sign-ups per product, broadcast reads, clicks and orders. Products with long waitlists tell you what to reorder in larger quantities.

Our pick: Tadlo AI

Tadlo AI

Our top pick

Best for: Restock broadcasts

Tadlo AI sends restock alerts as broadcasts on its Growth plan, ₹2,499 a month, shows the cost before you send, excludes opted-out customers, and adds no markup on Meta's charges. You select the waiting segment and send; it is not an automatic stock trigger.

Price: Free forever plan with up to 10 messages a day. Starter ₹999, Growth ₹2,499, Pro ₹5,999 and Scale ₹11,999 a month, priced on unique contacts engaged per month. Meta's message charges are billed by Meta directly to your own account, and Tadlo adds no markup. Prices exclude GST.

Strengths

  • No markup on Meta's message charges: Meta bills your own WhatsApp Business Account directly, and Tadlo only charges a flat plan
  • Built for D2C: abandoned cart recovery, COD to prepaid nudges and order updates from Shopify and WooCommerce (Growth plan and above)
  • Instagram comments to WhatsApp chats, which most WhatsApp-only tools cannot do
  • Priced on unique people reached, not on every message, so you can follow up without counting sends
  • Number health checks every 15 minutes, gradual ramp-up for new numbers and automatic opt-out handling
  • Your WhatsApp Business Account is created inside your own Meta business account, so it stays yours

Limitations

  • Newer than AiSensy, WATI or Interakt, with a shorter track record
  • Commerce automations start on the Growth plan (₹2,499 a month)
  • Tadlo AI is onboarding brands in stages, and you request access on its WhatsApp page.

Visit Tadlo AI

Frequently asked questions

How do I send back-in-stock alerts on WhatsApp?

Collect a waitlist with WhatsApp opt-in per product, then send a restock broadcast to that segment when stock arrives.

Are restock alerts marketing or utility messages?

Marketing. They cost ₹0.8631 each to Indian numbers from 1 October 2026.

Can Tadlo AI send restock alerts automatically when stock changes?

We did not find an automatic stock trigger in Tadlo's published plans. You send restock alerts as opted-in broadcasts.

How do I build a restock waitlist?

Add a "Notify me on WhatsApp" option on sold-out pages and an Instagram keyword that leads to the same opt-in.

Sources

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