OpenedOrNot

OpenedOrNot is a free Gmail email-tracking browser extension (part of the 500apps suite) that tells senders the moment a recipient opens their message, using invisible pixel tracking to log opens, link clicks, read time, location, and device. It's aimed at sales teams, customer support reps, and freelancers who send outbound Gmail and want to know whether messages are actually being read. Its main differentiator is simplicity: green/grey read-receipt ticks and instant open notifications built directly into Gmail rather than a standalone analytics suite.