Windsor is a small historic community and unincorporated area located within Robbinsville Township (known as Washington Township until 2007) in Mercer County, New Jersey, United States. The area is served as United States Postal Service ZIP Code 08561. There are approximately 50 homes in the area, and as of the United States Census, 2000, the population for ZIP Code Tabulation Area 08561 was 314. While most of the locals have heard of neighboring West Windsor and East Windsor, few have heard of "just Windsor," which contributed to the naming of Windsor's community association website www. justwindsor. org.