optool.exe is Opera Tool. More information can be found here.

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Optool (formerly Operatool, now Optional Browser tool or Open-in-another-browser-tool - or whatever you like!) for MS Windows is a freeware utility which easily allows you to open a given web site in another browser. Use it if your preferred browser doesn't show the site properly or if you are a developer and want to check the page in several browsers without the hassle of cutting and pasting the URL. Additionally, version 2.0 adds some very useful features to navigate to the parent or root URL of the web site, or to close all windows of the current application or even all running browsers!