“Big data” research runs the risk of being undermined by the poor design of the digital identifiers that tag data. A group of worldwide researchers, led by Julie McMurry, at Oregon Health & Science University, has assembled a set of pragmatic guidelines to create, reference and maintain web-based identifiers to improve reproducibility, attribution, and scientific discovery. The guidance, publishing June 29 in the open access journal PLOS Biology helps address the frequent problems associated with persistent identifiers linked to scientific data.