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Problem

Many retailers offer price adjustment policies that let customers claim a refund if an item’s price drops within a set window after purchase. Almost no one takes advantage of these policies because they don’t know the price dropped, or the process feels like too much effort. Money is left on the table.

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Solution

Use SKU-level transaction data from Knot’s Sync Transactions endpoint to detect when the same product is purchased at a lower price by another user at the same retailer. When a price drop is detected within the retailer’s adjustment window, proactively alert the original buyer so they can claim the difference.
Push notification alerting a user that a product they purchased recently has dropped in price, with the savings amount and a prompt to claim the refund
This surfaces real savings opportunities that users would otherwise miss, driving engagement and reinforcing the value of your app.

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Flow

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Implementation

1

Sync transaction data

When a user switches their card at a merchant or they simply link their merchant account w/o switching their card, Knot begins collecting transaction data for that account. Listen for the NEW_TRANSACTIONS_AVAILABLE webhook event, then call Sync Transactions to sync SKU-level transactions on a daily basis. Each transaction includes an array of products with prices and unique identifiers.Key fields
FieldPurpose
products[].external_idUnique product identifier for cross-user price matching.
products[].nameProduct display name for the alert.
products[].price.unit_pricePer-unit price paid.
datetimePurchase timestamp for policy window calculation.
merchant.idIdentifies the retailer for scoping comparisons.
merchant.nameRetailer display name for the alert.
external_user_idIdentifies the user who made the purchase in your system.
external_idOrder number, useful for pre-filling claim forms.
order_statusFilter to completed orders only.
Only include transactions with order_status of COMPLETED, DELIVERED, PICKED_UP, SHIPPED, BILLED, or ORDERED. Filter out CANCELLED, REFUNDED, and FAILED.
2

Detect price drops

On each incoming transaction, check whether any previously purchased product (by any user, at the same merchant) was bought at a higher price within the retailer’s adjustment window.
FOR each product in new_transaction.products:

    matches = find all prior purchases WHERE
        prior.products[].external_id == product.external_id
        AND prior.merchant.id == new_transaction.merchant.id
        AND prior.datetime > (today - POLICY_WINDOW_DAYS)
        AND prior.products[].price.unit_price > product.price.unit_price

    FOR each match:
        savings = match.unit_price - product.unit_price
        IF savings >= MINIMUM_SAVINGS:
            trigger price drop alert for match.external_user_id
This works because Knot aggregates transaction data across all your users. If user B buys the same product at a lower price than user A did last week, user A can claim the difference. The crowd-sourced transaction data provides the price signal.Configuration decisions for your team:
ParameterSuggested DefaultConsiderations
POLICY_WINDOW_DAYSVaries by retailerApply the correct window per merchant. Common examples: 14 days for general retailers, 30 days for warehouse clubs.
MINIMUM_SAVINGS$5.00Keeps alerts meaningful and avoids notification fatigue for small amounts.
Alert frequencyOnce per opportunityDon’t re-alert if the price drops further, or optionally send a follow-up with updated savings.
Trigger timing options:
  • Real-time: Run the check on each incoming transaction. Alerts surface within minutes of a price drop being detected.
  • Batch: Nightly scan of all purchases in the trailing policy window. Simpler to implement but delays alerts by up to 24 hours.
  • Hybrid: Real-time for high-value drops (>$10), batch for smaller amounts.
3

Alert the user

When a price drop opportunity is detected, notify the user with the product name, original price, current price, savings amount, and days remaining in the adjustment window.
Push notification alerting a user that a product they purchased recently has dropped in price, with the savings amount and a prompt to claim the refund
Deeplink the user to a screen displaying the full details of the price drop, including the order number (external_id) and a link to the retailer’s price adjustment form to claim the refund. Better yet, use Knot’s API to submit the refund request through the merchant prior to notifying the user.

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Expansion Path

  • Automated claim submission: Instead of alerting the user, submit the price adjustment claim on their behalf automatically through Knot’s API. Once the refund is processed, notify the user that money is already on its way, no action required. This eliminates friction entirely and maximizes claim rates.
  • Price tracking alerts: Even for retailers without formal price adjustment policies, alert users when a product they bought drops in price. This is useful as a general spending awareness feature that reinforces the value of your app.