HELL'S KITCHEN, Manhattan — A group of frustrated residents are suing the landlord of their Hell's Kitchen apartment building because they don't want to use an app to get into their building; they just want keys.

Tenants need to use Latch on their smartphones to get into the West 45th Street building. Artist Marybeth McKenzie, 72, has lived in the building for nearly five decades.

"We just want a key," she said. "We've always had a key."

Her 93-year-old husband doesn't even have a smartphone and has become a shut-in because of the new system.

"He cannot use a cellphone so for him it's really important to have a key," McKenzie said.

Latch is used in at least 1,000 apartment buildings across the city and many newer tenants of the 45th Street building don't mind using the app to access the building lobby, elevator and mailboxes.

“It works so well,” Anna Paola Sambaio, a tenant of just one month, told PIX11 News. “I don’t have any concerns."

But the lawyer representing the residents who've filed a suit against landlord Shai Bernstein says the app is a harassment tactic to force out rent-regulated tenants.

"[It's] an attempt to surveil the tenants by forcing them to use a electronic key system that includes GPS function that tracks their whereabouts and requires them to provide sensitive conditional personal information to use the system," the lawyer said in a statement.

Bernstein declined to comment because of the ongoing lawsuit.