Download of Free MKV to MP4 Converter 5.1.23 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software lies within Audio & Video Tools, more precisely Editors & Converters. This free software for Mac OS X was originally created by 4Videosoft Studio. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Free MKV to MP4 Converter can convert MKV video files to MP4, MOV, M4V and audio formats like MP3, AAC, M4A, OGG to enjoy on portable devices like iPhone 6/6 Plus, iPad Air 2, iPad mini 3, iPod Touch, iPod Nano and more.
You may want to check out more software for Mac, such as Leawo Free MKV to iPhone Converter, Leawo Free MKV to iPod Converter or MacX Free DVD to MP4 Converter for Mac, which might be similar to Free MKV to MP4 Converter.