Mapbox GL JS SDK uses the browser local storage system and keys prefixed with mapbox.eventData to store telemetry-related data. This data includes a randomly-generated ID that is included in telemetry events that are sent to Mapbox in order to calculate aggregate usage statistics; as well as metadata about telemetry events that is only used locally. This data is not sold to third parties, nor does Mapbox use the data (either alone or in combination with any personal identifiers) for advertising, tracking end users, or creating profiles of individual end users.