Most public parks in the city now offer free wi-fi. Some prominent ones include the High Line, Bryant Park, Battery Park, City Hall Park, Madison Square Park, Tompkins Square Park and Union Square Park (Brooklyn and Queens are also well covered). Note that although Central Park is technically covered, connectivity is poor. For other locations, check out www.nycgovparks.org/facilities/wifi.
Museums also often offer free wi-fi, as do underground subway stations. LinkNYC (www.link.nyc), rolled out in 2016 to replace anachronistic pay phones (once iconic symbols of the city and where Superman changed into his suit), has installed free internet-connected kiosks, replete with charging stations and wi-fi access. The network aims to install some 7500 of these structures throughout the five boroughs. Coverage is widespread in Midtown Manhattan, but gets increasingly spotty the further north or south you go, particularly in SoHo and the Lower East Side.
It’s rare to find accommodations in New York City that don’t offer free wi-fi these days. Most cafes offer wi-fi for customers (though they may not always advertise it), as do the ubiquitous Starbucks around town.