Freeware (Premium Available)
Windows / Mac / Chrome OS
It's rare for a piece of freeware to come in a form that completely negates the reason for the paid version, but for day to day use, Grammarly is does just that.
Available as a native download or a browser plug-in, as well as an add-in for Microsoft Office, Grammarly offers a spectacular upgrade to the spelling and grammar offering native to your operating system, with a more intelligent engine, a mouse-hover suggestion with one-click accept and if you prefer, a full screen interface where it explains why it feels you should write what it suggests.
Additionally, it's packed with proper nouns, specialist terms and slang - all the things that standard checkers lack, but because it's cloud-based, it can use a bit of AI magic to deduce context.
The paid for version is designed to appeal to academics, scholars and technical writers, but for the rest of us, Grammarly is amongst one of the best pieces of freeware of any kind that we've seen and should grace any computer.