Keystone is a home rule town[5] located in Summit County, Colorado, United States.

Keystone residents voted to incorporate on March 28, 2023, becoming a municipality on February 8, 2024.

The population of the former Keystone census-designated place (CDP) was 1,369 at the United States Census 2020.

The Dillon post office (Zip Code 80435) serves Keystone postal addresses.

The summer activities include hiking, mountain biking, fishing, trail running, golf on two championship courses, and paddle boating on Keystone Lake.