The London founded startup Citymapper has raised a new round of funding from venture capital investors worth $40m (£28m).
Index Ventures and Benchmark Capital have funded the series B round along with Yuri Milner, Tom Stafford and Michael Lynton.
The hugely popular app founded in 2010 uses data to give users real-time travel information.
It will use the investment to expand its product and enter new markets. It currently serves 30 cities. It will also work on new products.
The valuation of the company was not revealed with the new funding. It said in a blog post: "We’re not a unicorn. We’re more like a dolphin."