Badge Counter for Gmail is a Chrome extension developed by InBasic. This free add-on and tool falls under the category of browsers. It provides users with a badge counter for a custom user search query in Gmail.

With this extension, users can see the number of unread emails from multiple Google accounts displayed in the badge area of the toolbar button. The search query used is equivalent to "is:unread label:inbox". The extension does not store user credentials for privacy reasons, but instead utilizes the active Gmail session to perform searches. It is important to note that users need to be logged into at least one Gmail account for the extension to work.

Badge Counter for Gmail also supports multiple account access, allowing users to view the number of unread emails for all logged-in accounts. Users have the flexibility to define multiple search queries for each account from the options page, with the badge number representing the total number of search items.

Clicking on the toolbar button opens the most recent Gmail thread, which can be configured from the options page. For accessing other Gmail accounts, users can utilize the right-click context-menu items.

This extension is particularly useful for those who require a powerful Gmail notifier, rather than a full-fledged Gmail client.