We construct a new measure of voluntary disclosure based on firms’ websites. Using the Wayback Machine, we create a standardized measure of disclosure capturing the quantity of information on firms’ websites. We validate our measure by documenting that it is positively associated with established measures of firms’ voluntary disclosure and liquidity. Importantly, we document that our measure, while correlated with established disclosure measures, is not subsumed by those measures. It complements existing measures in three important ways. First, our measure captures not only capital-market-related but also additional information geared toward stakeholders other than investors (e.g., customers). Secondly, our measure can be calculated for a broader sample of firms, including small, private, and international firms. Lastly, our measure can be customized to fit the specific research question at hand (e.g., ESG disclosures) via textual analysis of website content.