A woman's boyfriend and her grandpa have melted hearts online after a clip of them working together to build a "catio" for her indoor feline quickly went viral.

The video, shared on TikTok in July under the username @samsimpsonx, shows the two men building the catio from scratch, right outside of the poster's kitchen window.

They assemble the screen panels, screwing them safely to the wall, adding shelves for the cat to climb, and even a layer of fake grass at the bottom.

More From Newsweek Vault: The Top Rewards Credit Cards for Pet Owners

The result is outstanding and the cat can be seen in the clip immediately falling in love with his new outdoor area, climbing and playing as if he'd always had one.

"My grandpa and boyfriend built a little catio for my indoor cat," says a caption shared with the heart-warming clip.

Dr. Nita Vasudevan, veterinarian at Embrace Pet Insurance told Newsweek that catios can be an excellent and safe option for indoor cats.

More From Newsweek Vault: Best Pet Insurance for Cats

"They provide a secure environment where cats can enjoy the outdoors without the risks associated with free-roaming, such as traffic, predators, or exposure to diseases," she said. "They allow cats to experience the sights, sounds, and smells of the outside world, which can be very enriching and beneficial for their mental and physical well-being."

As Vasudevan explains, cats don't need outdoor time in the same way some other animals might, but it can be highly beneficial.

More From Newsweek Vault: Compare Affordable Pet Insurance Plans

"Outdoor time provides mental stimulation, exercise, and the opportunity to express natural behaviors like climbing, hunting, and exploring," she said. "However, this can be achieved safely with a catio or by supervised outings on a leash.

"For cats that aren't given outdoor access, it's important to ensure they have plenty of indoor enrichment, such as toys, climbing structures, and interactive play"

A good catio, according to Vasudevan, should prioritize safety, space, and stimulation.

"The structure should be escape-proof and made from durable materials that can withstand weather conditions," she said. "The mesh or screening should be strong enough to keep your cat in and other animals out. It should be large enough for them to walk, climb, and stretch out comfortably. Vertical space is particularly important, as many cats enjoy climbing.

"Access to sun and shade, as well as a good view of birds or other wildlife, can also make the space more enjoyable for your cat. The catio should always be easily accessible from your home, perhaps through a window, door, or cat flap. This allows your cat to move in and out freely, as well as giving you easy access for cleaning, maintenance and monitoring."

Custom-made catios generally cost between $3,000-$10,000, while DIY ones can be cheaper than $500, according to statistics shared by PangoVet.

The video featuring the catio quickly went viral on TikTok, receiving over 3.7 million views and 234,200 likes on the platform.

Some users criticized the poster's choice to limit her cat's outdoor playing area to the enclosed catio. One, sh.ypa, commented: "[Humans] don't deserve animals they are not like you to sit and chill, they want run hunt play see nature feel the ground."

But others, aware of potential dangers, commented in defense of the poster. Sammie Jayne said: "My cat is an indoor cat, if the world was a nicer place we could let them outside but unfortunately people are cruel, we want to protect our babies! Nothing wrong with that."

Anna Hutchins added: "I had four cats my 1 Indoor cat lived to 21 my 3 outdoor cats all died by age 10, sammi knows what is best for HER cat."

Newsweek reached out to samsimpsonx for comment via TikTok comments. We could not verify the details of the case.

Do you have funny and adorable videos or pictures of your pet you want to share? Send them to life@newsweek.com with some details about your best friend and they could appear in our Pet of the Week lineup.