HeinOnline, sometimes spelled Hein Online, is an internet service launched in 2000 that is a source of legal information, much like Westlaw and LexisNexis. Like those services, HeinOnline requires a subscription. It is published by William S. Hein & Co and provides access to a large number of law libraries.
There are three major distinctions between this service and other such services in terms of the scope and type of materials offered.
HeinOnline provides a narrower scope of materials, excluding newspaper reports, as well as most federal and all state case law and most administrative material.
With respect to law reviews, HeinOnline is far more comprehensive, with material that in some cases stretches back to the mid-19th century.
HeinOnline's materials are available only as PDF files, digitized scans of the original journal pages. While HeinOnline does not offer a keyword search per se, it does have a full-text OCR search capability.