BTC Price Check is a Chrome add-on developed by William Jagels. It falls under the category of Browsers and is specifically categorized as an Add-ons & Tools.

This handy add-on fetches and displays the last, bid, and ask prices of Bitcoin. It does so by grabbing API data from Bitfinex's public API and presenting the information in a neat and organized window. Users have the option to enable automatic refresh, which updates the price every half-second.

BTC Price Check is an open-source project, which means that its source code is freely available on GitHub for anyone to access and contribute to. The add-on provides a convenient way for Bitcoin enthusiasts to keep track of the latest prices without having to navigate away from their browser.

Overall, BTC Price Check is a straightforward and practical tool for monitoring Bitcoin prices in real-time.