21st Amendment Brewery is a craft brewery and restaurant located in San Francisco's South Park neighborhood, founded in 2000 by Nico Freccia and Shaun O'Sullivan. The brewery's name pays homage to the 21st Amendment, which repealed Prohibition. It started as a brewpub and has become a local favorite, known for its lively atmosphere and Americana-themed decor. The original brewpub serves as a hub for small-batch brewing and innovation.

The brewery produces a range of handcrafted beers, including popular options like Hell or High Watermelon Wheat and Brew Free! or Die IPA. Since 2015, production has been centralized in a large facility in San Leandro, California, which has a brewing capacity of 150,000 to 180,000 barrels annually. This facility also features advanced packaging technology and supports national distribution and co-packing services for other beverage brands.

21st Amendment Brewery is recognized as a pioneer in the craft beer movement and has received numerous awards for its offerings. It serves a diverse customer base, including local residents, tech workers, and craft beer enthusiasts across the country.