Opportunity Cost by TFTC, Moses

Think in sound money, everywhere you browse.
Opportunity Cost instantly shows the price of products and services in bitcoin ( ₿ / sats ) next to the original fiat amount. No more mental math or tab-hopping to converters—just a constant reminder of what spending really costs in Bitcoin terms.

Key features

Automatic price detection & conversion – Detects 10+ local currencies and shows the live satoshi equivalent right on the page.

Real-time rates – Pulls spot prices from reliable Bitcoin exchanges every ~30 seconds for up-to-date conversions.

Inline or tooltip display – Choose a subtle gray sats value beside the price, or a tooltip that appears on hover.

Dark mode support – Looks great in light or dark themes, automatically matching your browser’s appearance.

Quick toggle – Click the toolbar icon to pause/enable on the current site or everywhere.

Customisable – Pick your preferred currency, number format (sats / BTC), display precision and refresh interval.

Zero sign-up, zero tracking – We collect no personal data. All parsing and settings storage happens locally (via IndexedDB); the only outbound request is for a BTC/FIAT price feed.

Open-source – View the code, file issues or contribute on GitHub.

Permissions note
This extension uses the tabs permission solely to support per-site toggling, allowing you to enable or disable Bitcoin pricing on specific websites.