The CashBackStacks Browser Extension: Your Real-Time Stacking Advisor

#What the Extension Does

The CashBackStacks browser extension turns every online shopping session into an optimized cashback opportunity. When you visit any of the 48,000+ stores in our database, the extension automatically:

1. Identifies the store and pulls live rates from 50+ cashback portals
2. Matches your saved credit cards to the store's merchant category for the highest reward rate
3. Surfaces activated card-linked offers from your synced accounts (Chase, Amex, Capital One, Citi, PayPal, SimplyMiles)
4. Checks gift card discounts from 14+ providers and compares the gift card path against the portal path
5. Presents your optimal stack: the specific combination of portal, card, and offers that maximizes your total return

The extension is available for both Chrome and Firefox with identical features on both browsers.

#The Shopping Widget

The core feature is the on-page shopping widget: a compact overlay that appears when you visit a supported store. It shows your full cashback stack in real time:

Portal Layer: The widget displays the best portal rate available, with a one-click activation link that opens the portal's referral flow. Rates are compared across all 50+ tracked portals automatically, so you never have to check each one manually. For a deep dive on how portal rates work, see the cashback portals guide.

Credit Card Layer: Based on the store's merchant category code (MCC), the widget identifies which card from your saved portfolio earns the highest rewards: a 5% grocery card at a grocery store, a 3% dining card at a restaurant. The right card is surfaced automatically. Learn how to build the optimal card portfolio in the credit card portfolio guide.

Card-Linked Offers: Any active offers from your synced accounts are displayed with their value. This includes issuer CLOs, PayPal Offers, and SimplyMiles, all in one view so you never miss free money.

Gift Card Path: When a discounted gift card produces higher total savings than the portal path, the widget flags it and shows the comparison. See the gift card stacking guide for the full strategy.

Here is an example of what the extension produces for Best Buy: a live stack breakdown:

#Multi-Source Offer Sync

The extension syncs card-linked offers from six major sources, each with different binding behavior:

The sync process runs on demand (you trigger it) via extension popup or extension sync widget (that appears when you visit a bank's website offer page), or via the website (after installing the extension). You can also activate supported offers directly from the extension or website without visiting each bank's website individually and manually activating offers.

#Toolbar Badge

The extension displays a small badge on its toolbar icon showing the best available cashback rate for whatever site you are currently browsing. At a glance, you can see whether a store has cashback available and roughly how much, without opening the widget.

The badge uses the same stack calculation logic as the full widget, so the number reflects your actual best option (portal rate, gift card discount, or combined stack value) given your saved preferences.

#Search Engine Badges

An optional feature that annotates search engine results with cashback rates. When you search on Google or other supported engines, small badges appear next to results for stores in the CashBackStacks database, showing the best available cashback rate.

This helps you factor cashback into purchase decisions before you even visit a store, which is especially useful when comparing retailers for the same product.

#Issuer Sync Widget

When you visit a bank's website (Chase, Amex, Capital One, Citi) or a shopping offer site (PayPal, SimplyMiles), the extension displays a small floating widget that lets you:

• See your last sync time and offer count for that source
• Trigger a fresh sync with one click
• Activate available offers directly
• Check permission status

This eliminates the need to remember to sync each source separately. The extension surfaces the sync option right where the data lives.

#Card Portfolio Management

Your credit card portfolio lives in the extension and powers the per-store card matching. You can:

• Add cards from the full catalog of tracked credit cards
• Remove cards you no longer carry
• See category bonuses for each card in your portfolio

The extension uses each card's bonus category structure and the store's MCC to determine which card earns the most at every store you visit. This matching is the same logic used on every store page on the website. For strategy on building the right portfolio, see the credit card portfolio guide.

#Watchlist and Alerts

The extension supports store-level watchlists with real-time notifications:

• Rate spike alerts: Get a browser notification when a portal rate for a watched store jumps above its historical baseline
• Product price drop alerts: Track specific products (e.g., on Best Buy) and get notified when the price decreases
• Target rate alerts: Set a threshold rate and receive a notification when any portal reaches it

Watchlists are available on the free tier (up to 3 stores) and unlimited on Premium.

#Website Bridge

The extension connects to the CashBackStacks website through a secure in-browser message bridge. When both are active, the website reads your extension data locally to personalize the experience:

• Synced offers appear on store pages and in the Best Stacks feed
• Your card portfolio drives personalized card matching across the entire site
• The AI assistant uses your cards and offers to provide personalized recommendations
• Watchlist changes made on the website reflect in the extension and vice versa

Your data never leaves your browser. The bridge is a local communication channel between the extension and the website tab; no card details, offer data, or browsing activity is transmitted to CashBackStacks servers. Set up your portfolio and sync sources once in the extension, and the website picks it up automatically through this local bridge.

#Free vs. Premium

#Install and Get Started

The extension is available for both major browsers with identical features:

• Install for Chrome: Chrome Web Store
• Install for Firefox: Firefox Add-ons

After installing, use the calculator below to model your first stack and see how the extension automates this for every purchase:

Here are today's hot deals, surfaced through the extension's notifications and toolbar badge: