Pronto

Pronto is a free Firefox extension that brings you instant price comparisons when you shop online Pronto is a free Firefox extension that brings you instant price comparisons when you shop online via a small message window that alerts you of potential savings. With over 40 million products from 50,000 merchants, Pronto is the most comprehensive product search online.

Pronto lets you:

- instantly compare prices as you shop online;
- automatically save with exclusive coupons delivered while you shop; and
- set Price Alerts and we\'ll email you when a product hits your target price.

Note that Pronto currently only works for retailers selling in US dollars.