Grammarly was originally launched as a subscription service for students, although the platform has moved into the mainstream in the last decade. It went freemium in 2015 and now works across more than 500,000 applications and websites including email clients, enterprise software, and word processors. Paid tiers give users more tools beyond grammar and spelling checks to include things like word choice, sentence rewrites, tone adjustments, fluency, and formality level.

The company has been profitable since the beginning and now has a valuation of more than $13 billion, placing it among the 10 most valuable startups in the US. The AI writing assistant space is heating up, and Grammarly is hoping to defend its positions against offerings including Scalenut, Ginger and Microsoft's Editor by the release of its SDK, making it far easier to integrate Grammarly into other applications. So far this has been used in over 4,000 products and earned excellent ratings and increased user numbers of Grammarly's service.