American singer Taylor Swift, who released a surprise ninth studio album, Evermore, last Friday (Dec 11), turned 31 on Sunday.

Many of her celebrity friends and fans sent her birthday greetings.

American actress Blake Lively shared a personal snapshot of the singer on social media, as she wrote: "There was happiness because of you. Happy happy birthday.

"Thank you for #Evermore. Absolutely nothing better than getting presents on other people's birthdays."

Swift's long-time friend, model Gigi Hadid, posted on Instagram Story a picture of them in pyjamas. "Happiest 31st year, my T! Wish we could be together to celebrate. Love you so much."

American Idol host Ryan Seacrest posted on Twitter a photo of him with Swift and wrote: "Happy birthday @TaylorSwift13! Wishing you a day so special, it becomes folklore and remembered evermore."

Other celebrities who wished Swift happy birthday included actor Ryan Reynolds, actress Cara Delevingne and TV host Ellen DeGeneres.

Acknowledging her birthday on social media on Sunday, Swift gave fans another surprise: a new remix of her single, Willow, which was just released together with Evermore last Friday.

The multiple-Grammy winner wrote: "Not to be all 'iTs mY BiRtHdAY & I jUsT wAnNa DaNcE' but... it is and I do. So we've released the willow dancing witch version, remixed by Elvira, a bad ass female producer I really respect."