Corrects the year Grammarly was founded in paragraph 3, and the spelling of CEO's first name in paragraph 6;

By Krystal Hu

July 1 (Reuters) - Grammarly has signed a deal to acquire email efficiency tool Superhuman as part of the company's push to build an artificial intelligence-powered productivity suite and diversify its business, its executives told Reuters in an interview.

The San Francisco-based companies declined to disclose the financial terms of the deal. Superhuman, once an exclusive email tool boasting a long waitlist for new users, was last valued at $825 million in 2021, and currently has an annual revenue of about $35 million.

Grammarly's acquisition of Superhuman follows its recent $1 billion funding from General Catalyst, which gives it dry powder to create a collection of AI-powered workplace tools. Founded in 2009, the company has over 40 million daily users and an annual revenue exceeding $700 million. It's working on a name change with an ambition to expand beyond grammar correction.

Superhuman, with over $110 million in funding from investors including IVP and Andreessen Horowitz, has been trying to create an efficient email experience by integrating AI.

The company claims its users send and respond to 72% more emails per hour, and the percentage of emails composed with its AI tools has increased fivefold in the past year. It also faces growing competition as email giants from Google to Microsoft are adding more AI features.

"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 Shishir Mehrotra, CEO of Grammarly. "Superhuman is the obvious leading innovator in the space."

Last year’s purchase of startup Coda gave Grammarly a platform for AI agents to help users research, analyze, and collaborate. Email, according to Mehrotra who co-founded Coda, was the next logical step.

Superhuman CEO Rahul Vohra will join Grammarly as part of the deal, along with over 100 Superhuman employees.

“The Superhuman product, team, and brand will continue,” Mehrotra said. “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 that the deal will give Superhuman access to “significantly greater resources” and allow it to invest more heavily in AI, as well as expand into calendars, tasks, and collaboration tools.

Mehrotra and Vohra see an opportunity to integrate Grammarly’s AI agents directly into Superhuman, and build the tools for enterprise customers.

The vision is for users to tap into a network of specialized agents, pulling data from across their digital workflows such as emails and documents, which will reduce time spent searching for information or crafting responses. The company is also entering a crowded space of AI productivity tools, competing with tech giants such as Salesforce and a wave of startups.

(Reporting by Krystal Hu in New York; Editing by Saad Sayeed)