The company's app, which launched in April on Apple iOS and is expected soon for Android, promises to help subscribers squeeze more information and entertainment out of a given number of downloaded bits. It may grow increasingly relevant in the U.S., where mobile operators are now phasing out unlimited data plans, but there are two major limitations on the tool right now: It can't compress video or Internet voice calls yet.

Onavo operates a cloud-based service that intercepts data headed for a user's smartphone and compresses it using specialized algorithms, said co-founder and CEO Guy Rosen. The service can reduce the amount of data a user consumes by as much as 80 percent, depending on the application and other factors, the company claims. Onavo has applied for patents on the compression algorithms it uses, Rosen said.

The approach is similar to that used by Opera, the mobile browser provider that uses a proxy server to compress websites. Onavo extends that concept to apps and plans to become an "Opera for everything," Rosen said. Apart from currently excluding video and VoIP (voice over Internet Protocol), the service can handle all types of data except encrypted bits, which in most cases are just the packets exchanged during login sessions for various apps such as Facebook, he said. When new mobile apps become popular, the company tunes its software to deal with those specific apps.

However, where Opera has focused on improving browser performance, Onavo is taking direct aim at phone bills, especially for international roaming.

"The point is really to help people save money," Rosen said.