Grammarly is a writing assistant that checks grammar, spelling, tone, and clarity in real time as people type, and it works essentially everywhere — as a browser extension, a desktop app, and native integrations with Microsoft Office and Google Docs — rather than requiring text to be copied into a separate tool. Beyond traditional proofreading, it detects tone (flagging text that might read as harsh or overly casual for its context) and offers generative rewrite suggestions that can adjust the length, formality, or clarity of a passage on demand. Grammarly also includes plagiarism detection for academic and professional writing. Its free tier covers core grammar and spelling checks, with paid tiers adding advanced tone detection, generative features, and business-oriented style guides.