Postcrossing membership is free. When sending postcards, members write personalized notes that highlight aspects of their hometown, their interests, or their lives. When receiving cards, members are encouraged to enjoy the surprise. They may discover something new about an unfamiliar city, learn more about the history of another country, encounter a work of art for the first time, or glimpse a moment in the life of someone on the other side of the world.

Today, an international team helps maintain the Postcrossing website, and the worldwide human connections fostered by Postcrossing have led to a number of educational, historical, and philanthropic initiatives. In 2020, the year after celebrating the 150th anniversary of the postcard, Postcrossing co-launched the worldwide designation of October 1 as World Postcard Day, based on the date in 1869 when the first modern postcard was known to have debuted in the Austro-Hungarian Empire. Postcrossing has inspired school projects, museum exhibitions, and regular in-person meet-ups, and the website has helped raise funds for disaster relief and other causes.