Shopify tracks the discount codes that succeed — never the ones that fail. Discount Leak Monitor listens at checkout and captures every code a shopper types that doesn't exist, has expired, or won't apply to their cart. See which codes fail, how often, and the cart value at stake. It groups likely typos (SUMMER2O → SUMMER20) so you recover lost demand, and emails you when a code you rely on starts failing. Read-only and privacy-first — it never edits your live discounts or stores customer data.