Cloud API firm quietly joins the $1bn valuation club.
Twilio has become the latest Silicon Valley "unicorn" worth $1bn (£660m) after securing $100m in its fifth round of funding.
The valuation of the cloud company, which specialises in communication APIs (application programming interfaces), was revealed after it quietly put out a filing in Delaware later uncovered by the research firm VC Experts.
The documents showed that Twilio authorised almost 9 million new shares to be issued at a price of $11.31 (£7.5) on April 24, which would put the value of the company in excess of $1bn, a figure confirmed by an anonymous source to Forbes.
Since launching in 2008 Twilio has collected abundant funding and secured high profile customers like the taxi app maker Uber, which uses the firm’s technology to deliver messages to drivers and customers.
Though rumours of an initial public offering have circulated for several years those close to Twilio have played down the speculation, despite chief executive Jeff Lawson saying in 2013 that a listing would be "the next logical step".
Earlier this year Lawson told CBR: "When I started seeking funding for Twilio, the thing I heard over and over again is that developers are not buyers and have no spending power.
"We had a hypothesis that the developer toolkit is a powerful driver of business, and our growth to over a hundred million dollar run rate in 2014 is proof of that."