What's in your wallet?

It might be the ID NYC card -- the ultimate "rewards" card for a surging number of locals.

The ID NYC program was designed to provide government-issued photo IDs to people who desperately need government identification but have had difficulty getting it -- undocumented immigrants, primarily, but also homeless folks, formerly incarcerated people, teenagers and older adults.

But as a result of the sweeteners offered with the card -- free membership to museums, zoos and botanical gardens, and discounted memberships to city recreation centers and YMCAs -- it has also emerged as a hipster cultural credential.

It's proven to be a popular insider's passport for locals who are more than adequately credentialed, but appreciate the perks, swag, freebies and discounts the card confers.

Obtaining the card "is a no-brainer . . . it's so cool!" said Tiffany Sun, 32, a tech startup editor from Brooklyn Heights, who has already activated a free membership to the New York Botanical Garden and BAM.

The card's benefits (multi-borough library privileges, dance rehearsal admissions to the New York City Ballet and other perks) have inspired her to explore the "full breadth of cultural offerings in NYC," and visit boroughs other than her own, she said.

"It's the 'I am a New Yorker: Hear me roar!' statement card," joked Ryan Max, external affairs director for the city's Department of Cultural Affairs.

More than 30,000 free memberships at 33 cultural institutions have been activated to date.

Membership lasts for one year after activation of an initial visit, which must be made by Dec. 31; it is unclear yet as to what benefits may be activated by those joining after that point.

More than 400,000 ID NYCs (representing 5.5% of NYC's population) have been issued to New Yorkers 14 and older since registrations began in January, with another 54,885 registrations in the pipeline, making NYC's municipal card program the largest in the nation.

Although the application rollout was rocky, applying now is a fairly seamless experience, cardholders said.

While 37% of the city's population is foreign born, according to City Hall, the city has no idea how many of those who have obtained the cards have done so primarily to obtain identification, and how many just wanted to see the Basquiat exhibit at the Brooklyn Museum for free.

"We do not ask applicants for their immigration status," a spokeswoman explained in a statement.

Yet, it's clear that many longtime residents -- grateful to finally have a break in an increasingly costly city that is often rife with frustrations -- have signed up, too.

"I hadn't budgeted," for an annual membership to the New York Botanical Gardens, explained Kaela Gallo, 25, a visual experience designer from Bushwick, so discovering she could get one for free by obtaining an ID NYC card was a blessing.

Leah Schmerl, 43, said that using her card "gave me a positive impression of the de Blasio administration."

Schmerl, a public relations consultant from Brooklyn Heights, loves the card she received in March -- even though it mistakenly lists her as "male" and has her street name misspelled. The city, she said, is "basically giving you money. It's weird to me that everyone hasn't got one."

Schmerl has activated memberships at the Brooklyn Museum, the BAM Cinema Club and Brooklyn Botanic Garden and plans to activate more memberships before the end of the year.

About 2,900 free ID NYC memberships have been issued at the New York Botanical Garden.

And 487 ID NYC holders have been given free family memberships ("we're not offering individual memberships") to the Queens Museum with enrollments swelling each month, said Queens Museum deputy director David Strauss. "Everyone has seen a tremendous uptick as a result of this program," Strauss said.

Representatives for museums and city institutions said the free memberships were not unlike "trial periods" offered by gyms and sports clubs to lure people into signing up after a leisurely time experiencing their offerings.

"It's an entry point: At the end of the membership, we'll send a brochure out to the address of the cardholder," hoping to recruit them as paying members, explained Melissa West, marketing and communications coordinator for the Snug Harbor Cultural Center and Botanic Garden on Staten Island.