By now we're all used to seeing security cameras perched on rooftops, on street corners, in lobbies and countless other locations in big cities. Even in smaller towns. But what if there are cameras out there, watching you, that you can't see? 

Oh, there are. 

Thanks to a startup called Placemeter, there are cameras all over New York City, staring down at you from people's apartments. And you'd probably never know it.

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Placemeter's "Meter" program offers individuals in NYC up to $50 a month to install a camera on a street-facing window in their apartment to record what's happening outside. It's looking to get a view of stores, restaurants and bars. And lots of people. 

On the front end, the system is super low-tech. Placemeter says participants use a suction cup to place an old cell phone to their window. Any old Any Android, iPhone or iPod Touch with a camera will do. Placemeter can provide the cell phone if a person doesn't have an old one handy, but it will deduct one month's payment for supplying it.

From there, the phones connect to the Placemeter app which feeds the images and data the phone captures back to Placemeter. It is run through the company's image-recognition algorithms, which can discern between pededstrians and cars and storefronts.

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Then, apparently, Placemetter discards the data. "Placemeter’s technology and camera networks are not used to track individuals," the company says on its website. "We will not use our Meters’ data to identify any pedestrians through our video streaming...ever."

The skeptic in some of us might find that difficult to believe. Placemeter also doesn't capture information from inside a person's home -- only the goings-on outside the apartment, it says.

Placemeter was founded in 2012 by CEO Alex Winter and COO Florent Peyre. They say the idea is to help cities better understand how many people are in a space at any given time. Consumers can use it to know -- for instance -- how long the line at their favorite hamburger joint is or to record video of people driving too fast down the street.

One of Placemeter's first initiatives was to partner with NYC's "Business Atlas" program, which uses cameras to record foot traffic in all five boroughs. In addition to foot traffic, the program aims to supply users with information such as neighborhood-level population and income. 

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For entrepreneurs, this can be a handy tool for market-research or for making location-specific business decisions.

Of course, other companies, like ShopperTrak, have been tracking and analyzing foot traffic in and around businesses for decades.

Placemeter wouldn't say how many people are participating in NYC's Meter program, but a representative pointed out that the company has more than 700 "viable applications." Beyond NYC, Placemeter aims to expand to other cities in the U.S. and abroad. The representative did not say which cities the company is targeting first.

Either way, Placemeter has its eyes on you.

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