SAN FRANCISCO, California: Grammarly is doubling down on AI-powered productivity tools with the acquisition of Superhuman, a sleek email startup known for its speed-focused interface and loyal user base.

The move marks Grammarly's latest step in building a comprehensive platform for professionals, expanding beyond its roots in grammar correction.

The San Francisco-based companies declined to share the financial terms of the deal. Superhuman, once famous for its invite-only exclusivity, was last valued at US$825 million in 2021 and currently brings in about $35 million in annual revenue.

Grammarly's acquisition follows a $1 billion investment round led by General Catalyst, giving the company fresh capital to assemble a suite of workplace tools powered by artificial intelligence. Founded in 2009, Grammarly now boasts over 40 million daily users and more than $700 million in yearly revenue. A name change is also being worked on as it aims to rebrand around its expanding capabilities.

Superhuman has raised over $110 million from investors including Andreessen Horowitz and IVP. Its focus has been on reimagining email for speed and efficiency, with a growing emphasis on AI. The company claims that its users send and respond to 72 percent more emails per hour, and that AI-generated emails on its platform have increased fivefold over the past year.

"Email continues to be the dominant communication tool for the world. Professionals spend something like three hours a day in their inboxes. It's by far the most used work app, foundational to any productivity suite," said Grammarly CEO Shishir Mehrotra. "Superhuman is the obvious leading innovator in the space."

Grammarly previously acquired startup Coda, which laid the groundwork for building AI agents to assist with research, analysis, and collaboration. Email, Mehrotra said—who also co-founded Coda—was a natural next frontier.

Superhuman CEO Rahul Vohra and more than 100 employees will join Grammarly as part of the acquisition. "The Superhuman product, team, and brand will continue," Mehrotra confirmed. "It's a very well-used product by tens of thousands of people, and we want to see them continue to make progress."

Vohra said joining forces with Grammarly will give Superhuman "significantly greater resources" to deepen its AI features and broaden its offerings to include calendars, task management, and other collaborative tools.

Both companies see the integration of Grammarly's AI agents into Superhuman as a significant opportunity, especially for serving enterprise users. The vision is to create a network of intelligent agents that can seamlessly access and process data across documents and emails, helping users reduce time spent searching for information or writing responses.