For Kevin and Leslie Espowe, Christmas once meant leaving out cookies for Santa before the kids went to bed. Last year, the couple graduated to a phone call from Santa -- actually a number Mr. Espowe saved on his cell phone as 'North Pole.' This holiday, the Espowes are going one better: editing a Santa image into a photo of their roof.

'It takes a bit more convincing now,' says Ms. Espowe, a 29-year-old mother of five girls from Union, Mo., who wants Santa to appear hurtling down an exposed pipe, since the house has no chimney. The Espowes will email the picture to their oldest daughter and have her show it to her sisters Christmas morning.

'Technology is definitely a good way -- they think if it's on the computer or a phone, it's real,' she says.

Video and photo editing, smartphone apps, email and other digital tools are gaining popularity as parents try to persuade their 21st-century kids that there is a Santa Claus. Technology can create evidence more convincing than fake reindeer tracks in the snow -- though without a deft touch, Santa can come off looking like a perp in a security video.

As adults seek slicker proof to back up the legends of childhood -- the existence of Santa, the Tooth Fairy, the Easter Bunny -- there's new confusion over the line between harmless fibs and outright deception.

'I want it to be playful and fun -- I don't want it to be the source of future therapy sessions,' says Amy Lupold Bair, whose four-year-old, Noah, often turns to the computer to back up his parents' assertions. (He said 'Let's Google that' at three). Last Christmas, she sent Noah an email from a 'Santa Claus' address. Noah was convinced, and this year had his mother type up his Christmas list in an email to Santa.

Other parents try documentary-style video. 'I said to my wife, it's got to be shaky and believable, you know, like that Big Foot video,' says Norm Hall, who filmed a scene last Christmas Eve with his wife, Alison, that starts with the two retrieving flashlights and looking out onto the dark yard.

'I'm a little afraid of going out there by myself,' Mr. Hall says in the video, pausing as he waits for a neighbor to appear in a Santa suit. After a few minutes, the flashlight beam captures a fleeting, jerky image of Santa running across the grass. Over his wife's screaming, Mr. Hall shouts, 'Get Jonny up!'

Mr. Hall, a 45-year-old father of three who is dean of students at Greenville College in Greenville, Ill., says his then-10-year-old son, Jonny, heard the commotion from bed, ran to the foyer in his Spider-Man pajamas and watched the video.

When developing 'Capture the Magic,' a Web service that allows people to upload a home photo and insert a Santa image into the picture, co-founder Jim Hallihan of Leesburg, Va., paid $1,500 for a Santa look-alike. A three-hour photo shoot put Santa in more than 150 poses, including hauling a bag of gifts, grabbing his belly and crawling on his hands and knees.

Charlie Taylor, a 44-year-old mom from Tigard, Ore., says her daughter Naelyn, now 19, recently revealed that she believed in Santa until seventh grade and got in fights on the elementary-school playground defending his existence. This holiday, Ms. Taylor is trying to preserve Santa for her now-doubtful 10-year-old son, Devin, by sending him a Santa video. She'll use 'Magic Santa,' a video service from Canadian media company Sympatico.ca that offers a menu of 1,478 names and other options to personalize messages.

'You're actually lying to your children, but if you think about it, Santa's more the spirit of giving, so I think it's nice for them to have something to believe in,' says Ms. Taylor.

A website, sendacallfromsanta.com, uses a menu to tailor a phone call from Santa that can even end with him saying 'Happy Hanukkah.' One hazard: Santa blows the secret at the end. 'This message was brought to you by Google Voice and someone you know who thought you might like it,' he says. The service is meant more for users to create playful phone greetings than to convince children Santa is real, says Google spokeswoman Lily Lin.

Simon Watson, a London-based salesman for a technology company, decided to tint Santa green as though captured by a night-vision camera to add realism to his iPhone app 'Elf Cam.' He created the app after last Christmas, when his then eight-year-old niece, Matilda, wanted to set up a trip wire to catch Santa on camera. The pressure is on to keep Matilda believing: 'I let it slip about the Easter Bunny this year and there were tears in the supermarket,' says her mother, Laura Watson.

Even parents who take a more traditional approach can get foiled by technology. Heather Peralta, a 34-year-old mother of two from Savannah, Ga., dropped Santa's glove outside the front door and left Santa's driver's license on the stairs -- part of a Santa 'evidence kit' she ordered online that arrived at the house in a plain brown box. After that 2008 holiday, she blogged about how her then nine-year-old daughter, Janson, bought the story and even insisted the family return the license via UPS.

When Ms. Peralta tried to pick up the ruse again last year, she recalls, Janson interrupted her: 'She said to me, 'It's OK Mama. I already know. I read about it on your blog.''