Downloading mouse34Btn 1.1.1.5182 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is Fiery. The application lies within Productivity Tools, more precisely Clipboard Tools. We recommend checking the downloaded files with any free antivirus.
From the developer:
mouse34Btn lets you use your 3-th and 4-th mouse buttons to Copy (Cmd+C) and Paste (Cmd+V) in all Mac applications that support these commands. It’s very lightweight and is meant to replace Logitech Control Center LCC or BetterTouchTool which otherwise are good apps, but are too heavy.
You may want to check out more Mac applications, such as AutoClips, ReClip or MayaMaya, which might be similar to mouse34Btn.