Methods and apparatus to supplement web crawling with cached data from distributed devices are disclosed. An example method includes identifying a first webpage. Accessing a set of cached webpages cached in a panelist device. When the first webpage is in the set of cached webpages: identifying a first language setting used by the panelist device when the first webpage was accessed. Transmitting a first number of requests for the first webpage, respective ones of the requests in the first number identifying different language settings. The requests in the first number of requests skipping the first language setting used by the panelist device when the first webpage was accessed.