DaVinci Resolve

High-powered cross-platform film editor – free and premium versions. Includes waveform syncing of multiple clips. Description from Macintouch:

DaVinci Resolve is professional, cross-platform video editing and production software from Blackmagic Design Pty. Ltd. with a powerful collection of features, including “Hollywood’s most advanced color corrector.” Editing features include various edit types (overwrite, insert, ripple overwrite, replace, fit to fill, append at end etc.) and styles “from drag-and-drop to the timeline, to three-point precision editing driven by customizable keyboard shortcuts”, multicam/multisource playback in a gridded window, finishing tools, VFX support and far more. The new version integrates Fairlight audio tools for recording, editing, mixing, sweetening, finishing and mastering, including 3D audio support. Resolve also includes multi-user collaboration features with individual logins, media management and support for specialized hardware control panels.
DaVinci Resolve 14 public beta 3 is available as a free download for OS X 10.11 and up, plus Windows and Linux. Resolve 12.5.5 is available as a free download in return for registering name, address, phone and email information, while DaVinci Resolve Studio 12.5 is priced at $299:

“The free version of DaVinci Resolve has all of the professional editing, legendary color correction and Fairlight audio tools you need for SD, HD and Ultra HD work at up to 60 frames per second. DaVinci Resolve Studio adds support for 4K and higher, along with frame rates up to 120 fps. It also includes dozens of additional image processing features and filters that are not in the free version. This includes film grain, temporal and spatial noise reduction, amazing new face enhancement tools, lens flares, lens distortion correction, optical quality blur and mist effects, match move, warping and much more!
Unlike cloud based software, DaVinci Resolve Studio does not require a connection to the internet and there are no monthly subscription fees. Now you can get DaVinci Resolve Studio for only $299, which is 50% less than the cost of popular cloud subscriptions. Plus, you get full nonlinear editing, advanced color correction and a massive suite of new Fairlight audio tools, all included in the one easy to buy solution.”