Grammarly predates the current AI writing boom by well over a decade. Three Ukrainian-born founders launched it in 2009 as a grammar and plagiarism checker aimed at students and academic writing, and it grew into one of the most widely installed browser extensions in existence long before generative AI became the industry's main pitch.
That history shapes what it's actually good at: real-time grammar, spelling, punctuation, and clarity correction as you type, inline and unobtrusive, across Gmail, Docs, Slack, and just about anywhere else text gets typed in a browser. Generative features arrived later, bundled as GrammarlyGO, letting users draft, rewrite, or adjust tone on demand, but the correction layer underneath is still the product's real foundation and what most of its user base actually opens it for.
The free tier covers core grammar and spelling checks and is genuinely usable long-term, not a bait-and-switch trial; the $12-a-month Premium tier adds tone detection, clarity rewrites, and plagiarism checking, while Business plans add brand style guides and admin controls for teams. Few tools in this category can claim Grammarly's install base or its decade-plus track record of just quietly catching typos before anyone notices them.
