Twitter has made its IPO S-1 filing publicly available, revealing that the company is shooting for an offering price of $1bn (£623m), with 472.6m shares of common stock set to be issued.

The filing also revealed that Twitter has 218.3m monthly active users – an estimated five per cent of which are spam accounts – 75 per cent of whom (around 164m) access the social network from mobile devices.

The company made $253.6m in revenue over the six months ending 30 June 2013, up 107 per cent year-on-year. Of that revenue, 13 per cent came from data licensing, with ads making up the remaining 87 per cent. The company isnt profitable, however. In the first half of the year, it made a net loss of $69.3m and $79.4m for the whole of 2012.

Mobile accounted for 65 percent of advertising revenue, around $143.4m. Thats well over half of Twitters overall income – a notable difference to Facebook, which at the time of its IPO had no mobile revenue.

“Mobile has become the primary driver of our business,” reads the Twitter filing. “Our mobile products are critical to the value we create for our users, and they enable our users to create, distribute and discover content in the moment and on-the-go. The 140 character constraint of a Tweet emanates from our origins as an SMS-based messaging system, and we leverage this simplicity to develop products that seamlessly bridge our user experience across all devices.”