Subscription Sentry — Email Sniffer

Scans Gmail, Outlook, and Yahoo Mail for suspected subscription receipts. A free companion to the Subscription Sentry app.

Subscription Sentry — Email Sniffer is a free, privacy-first tool that helps you discover the subscriptions hiding in your inbox. WHAT IT DOES With one click, the extension opens your Gmail, Outlook, or Yahoo Mail, runs a search for receipt-style messages, and lists the suspected subscriptions it finds — service name and price, nothing more. The list lives only in the extension popup on your device. You can then export the results as a JSON file and drop them into the Subscription Sentry app for full reporting, renewal tracking, price-change alerts, and analytics. WHO IT'S FOR - Anyone who feels they're paying for "something" every month but can't quite remember what - People who want a quick sanity check on their streaming, software, and news subscriptions - Subscription Sentry app users who want a faster way to populate their tracker PRIVACY - 100% local. No accounts, no logins, no servers, no cloud. - The extension never sends your data anywhere. Ever. - Email content is read in your browser, parsed in your browser, and the resulting list is stored only in your browser's local extension storage. - The only "network" the extension touches is the email provider tab you're already logged into. HOW IT WORKS 1. Click the Subscription Sentry icon in your toolbar. 2. Pick Gmail, Outlook, or Yahoo. 3. The extension opens the right inbox, searches for receipts, and shows the matches in a small popup list. 4. Optionally export the list as JSON for use in the Subscription Sentry desktop app. LIMITATIONS (PLEASE READ) - The scanner uses pattern matching, not AI. It may miss receipts in unusual formats and may flag the occasional one-time purchase. - Gmail, Outlook, and Yahoo update their interfaces from time to time. If a scan stops working, please report it — fixes ship quickly. - English-language receipts are best supported. PERMISSIONS, EXPLAINED - "Read and change your data on mail.google.com, outlook.live.com, outlook.office.com, outlook.office365.com, and mail.yahoo.com" — required to read the receipt search results from your inbox. The extension cannot access any other website. - "Storage" — used to cache your last scan results in your own browser, so the popup isn't empty when you reopen it. - "activeTab" / "scripting" — required to inject the small scanner script when you click a provider button. The extension does NOT request access to your bank, your credit cards, or any site outside the three supported email providers. ABOUT THE FULL APP Subscription Sentry (sold separately) turns the sniffer's output into a real dashboard: monthly cost totals, renewal calendars, price-change alerts, "haven't used in a while" warnings, bank statement import, and exportable reports. Look for it on Etsy, Gumroad, and other digital storefronts. NOT AFFILIATED WITH GOOGLE, MICROSOFT, OR YAHOO. "Gmail," "Outlook," and "Yahoo Mail" are trademarks of their respective owners.