A songwriter before she became a performer, Christina Perri blends singer-songwriter sincerity with studied pop tunesmith craft. That golden touch drove a trio of her songs — “A Thousand Years,” “Human” and “Jar of Hearts” — to sales in the millions.

Perri’s second album, 2014’s “Head or Heart,” features “Human” as well as “Be My Forever,” her duet with British singing heartthrob Ed Sheeran.

Prior to Perri’s 14-city U.S. tour with Sheeran in September, she’s appearing this summer with her talented friends, Colbie Caillat and Rachel Platten. Their “The Girls Night Out, Boys Can Come Too Tour” comes to Champions Square on Friday, Aug. 14.

Perri’s breakthrough came in 2010 with the placement of her ballad, “Jar of Hearts,” in an episode of “So You Think You Can Dance.” The song captivated the show’s viewers and went on to become a hit.

More success followed with Perri’s two albums, 2011’s “lovestrong.” and follow-up “Head or Heart.” As Perri approached the end of her album cycle for “Head or Heart,” she thought she hadn’t done enough touring for it. She’d previously supported “lovestrong.” with nine tours. She’d only done seven for “Head or Heart.”

“I was like, ‘OK, let’s fill the summer with a tour, a shed tour, outdoors, people bringing boxes of wine and blankets and hanging out,’ ” Perri said recently. She next thought about featuring Caillat and Platten on her projected summer on the road.

“We have so many similar messages in our songs,” Perri explained. “So, I was like, ‘Wow, this is a really cohesive show for us, and it’s fun because we’re all girls.’ ”

Caillat has won two Grammy awards and sold 6 million albums and 10 million singles. Her summery folk-pop-style hits include “Bubbly,” “Brighter Than the Sun” and “I Do.”

Platten’s empowerment anthem, “Fight Song,” is a hit this summer on iTunes and the Billboard’s Hot 100.

“Rachel is blowing up,” Perri said. “Which is amazing because I know her so well, and she’s been working hard for a really long time. I couldn’t be happier for her.”

Perri and Caillat weren’t friends before “The Girls Night Out, Boys Can Come Too Tour,” but they are now.

“Before, we’d only seen each other during events we did together or passing through cities, all these random things,” Perri said. “So when I went to her house and we just hung out, we realized we have so much in common.”

Perri and Caillat are alternating as each night’s closing act during the tour. They also share a stage set up because, during their pretour discussions, they discovered how similar their shows are.

“We both play white pianos, we both use white microphones and white stands and white instruments,” Perri said. “So we went in together on the production.”

And at some point during the show, Perri promised, she, Caillat and Platten will perform together.

Perri used her past tours as a basis for her “The Girls Night Out, Boys Can Come Too Tour” set.

“It’s our favorite parts of all the tours that we’ve done,” she said. “Little things that we loved, moments that we loved. We’re putting them all into one show.”