Broadway is enlisting an unlikely ally to help make shows accessible to the deaf and hard of hearing — the smartphone.

GalaPro, a Tel Aviv-based tech company, has created an app that puts a live closed-captioning system in the pocket of any theater attendee who needs it.

To use it, theater-goers need only download the free app and log onto the theater’s WiFi network. GalaPro will then automatically sync with the show, and display the play’s lines — and lyrics — onto the phone.

To avoid distracting those sitting nearby, the words are displayed in red on a black background.

To be sure, one theater-goer used the GalaPro last week at a showing of “Dear Evan Hansen.” Those seated nearby didn’t even realize the cellphone was on.

“Using phones in the theater is a huge deal,” GalaPro Chief Executive Yonat Burlin told The Post. “We’ve worked hard to make sure our product enhances the theater experience and doesn’t take away from it.”

Theaters pay GalaPro to have its technology installed — plus a monthly fee.

GalaPro recently signed a deal with the Shubert Organization after a successful test at “Avenue Q.” It is now available at Shubert’s 19 Broadway and off-Broadway theaters.

Before GalaPro, hearing-impaired customers could attend only select performances — and had to sit in a specific section near caption monitors. Now every seat and every show is available.

“The scalability of an app is really attractive,” Kyle Wright, the digital projects director for Shubert, told The Post. “We can say to the Broadway audience at large ‘as many people that want to come we can serve.’ ”

GalaPro has raised $3 million in funding, and is currently working on audio description services for the visually impaired, as well as translation services for theater-goers who don’t speak English.