This 1-Year-Old Startup Says It’s the Fastest-Growing Business App Ever

Office messaging service Slack, which is celebrating its first birthday Thursday, says it’s now the fastest-growing business app ever.

Slack has more than half a million daily active users sending 300 million messages a month on the platform, according a company press release. The app’s daily active user count has grown 35% since the start of the year, while it’s pulling in $12 million in annual reoccurring revenue.

Slack, valued at over $1 billion after a $120 million funding round last October, hopes to kill frustrating back-and-forth work e-mails with an easy-to-use chat interface. It also gives businesses a platform to upload and comment on posts and files, as well as integration with a wide range of productivity apps like Google Drive and Trello.

“Messaging has emerged as one of the most fundamental applications of the Internet, and its value is shifting into our work lives,” said Stewart Butterfield, CEO and co-founder of Slack, in a release. “Slack radically increases internal transparency and turns communication archives into a powerful shared resource.”

Slack justifies calling itself the fastest-growing business app based on analysis from Tomasz Tunguz, a partner at Redpoint Ventures who closely watches the corporate software space. The company’s stellar growth rate is especially notable because it’s happening almost entirely thanks to word of mouth and media coverage, not an aggressive advertising campaign.

Slack’s early success comes as more tech heavyweights are looking to expand their presence in the workplace. In January, Facebook introduced Facebook At Work, a revamped version of the social network meant to boost office productivity. Amazon recently announced a new cloud-based corporate email solution. And Box, a corporate file storage and sharing platform, went public late last month at a valuation of $2.7 billion.