Singer Taylor Swift wished good friend Lena Dunham a happy birthday in a touching Instagram post on Friday (13May16).

The Girls creator is part of the Bad Blood pop star's all-girl 'squad' inner circle, and Taylor made it clear how much Lena means to her in a sweet online message as the actress and writer hit her 30s.

"One of my favorite people in the world turns 30 today and I can't help but think about how different my life would've been without our long talks, arts and crafts projects, and running-into-each-others'-arms-hugs," the 26-year-old musician wrote. "Thanks for being you, Lena. Everyone who knows you is better because of it. HAPPY BIRTHDAY."

Taylor further emphasised her love for Lena by sharing a photo montage of the pals enjoying various hang-out sessions together. In the pictures, they hug at an awards show, eat a meal, and pose for a puckered up selfie together. The final shot features Lena cutting a birthday cake.

Meanwhile, Lena updated fans about how she was spending her 30th birthday on her own Instagram account.

The actress gave a shout-out to Girls co-writer Sarah Heyward, who gifted her a funny baseball cap inscribed with the words, "Read my hat No!". Lena praised the gift for its perfect representation of the vibe she is going for as she moves forward in her thirties.

"@shinyunicorn (Sarah) really gets what I'm going for in this new decade #HAT!" Lena wrote in a caption attached to a picture of herself wearing the red cap. "Also, thank you all for the bday wishes. It means more than I can say. You made my twenties a total dream."