Shiira (シイラ, Japanese for the common dolphin-fish) is a discontinued open source web browser for the Mac OS X operating system.

According to its lead developer Makoto Kinoshita, the goal of Shiira was "to create a browser that is better and more useful than Safari".

Shiira also uses Cocoa programming to provide users with a customizable drawer extending from the left or right of the window.

In version 2.0, the sidebar was replaced by a series of palettes opened and closed from the main window toolbar.

The interface in Shiira 2.0 could be set to display tabs as thumbnails along the bottom or sides of the window.