Darby Free Library is a public library at 1001 Main Street in Darby Borough, Delaware County, Pennsylvania. Founded as the Darby Library Company in 1743 – just 12 years after Benjamin Franklin organized the Library Company of Philadelphia – it remains one of the oldest libraries in the United States. Although it was a subscription library until 1898, it claims to be "the oldest library in the United States in continuous service." The library celebrated its 275th anniversary in 2018.