Streetline's parker app should consider modifying the first sentence on its webpage from "Download Parker and easily find and pay for parking" to "and pay for parking, if there's a charge".
Bill Silverfarb writes that "San Mateo has 135 sensors spread over four blocks downtown that will be in place for a two-year demonstration period as the city embarks on a long-range mission to improve the downtown experience." Perhaps Streetline chose San Mateo because it is based in adjacent Foster City, CA. The free app was developed "in partnership with Cisco, the free app uses sensors embedded in the street to provide real-time parking availability". San Jose-based Cisco is located 30 miles to the south.
While parking in downtown San Mateo is metered both on-street and in garages, nearby San Carlos (5 miles south on the San Francisco Peninsula) does not charge for parking. However, like most smaller cities, San Carlos does set time limits, so the parking app's "self-timer that shows the amount of time left to park at that location" may prevent you from receiving a parking citation.
"Sensors that provide real-time data have been installed in approximately 100 parking spaces on the first three blocks of Laurel Street in downtown San Carlos," according to the city manager's press release.
In addition to the two above Peninsula cities, Streetline's app will also be applied to the (metered) streets and garages of San Francisco, where sensors were installed as part of the innovative SF Park program, as Nate Berg explained in The Atlantic Cities last March:
"On-street parking spaces and city-owned garages are equipped with meters so the city can track occupancy rates and adjust pricing throughout the day. The city installed the system in 2010 and began varying its pricing last summer. The goal is to redistribute the demand for parking throughout the city. Web and phone applications make it easy for drivers to locate parking spots that are both open and at the desired price point."
Berg identifies many cities where Streetline's app is either in use or planned, but none as small as the two Peninsula cities described by Silverfarb.