The text of most reported, and many unreported, cases appear in several electronic sources.
Bloomberg Law, Lexis (Lexis Advance and Lexis.com), and Westlaw (collectively online legal research services) provide the full text of state and federal cases, with coverage extending as far back in time as most researchers usually need. They also provide access to unpublished opinions. Cases appearing on Westlaw include the headnotes and other "editorial enhancements" added by West to the cases in the print reporters. Lexis includes editorial enhancements for cases as well. Bloomberg Law has editorial enhancements like headnotes for some, but not all cases.
Though not as highly organized or comprehensive a source for case research as subscription online legal research services, there are many free web sites that supply the text of cases. For example, most federal and many state courts have web sites where the text of recently decided cases is available. There are some limiting factors in case research on the Internet compared to online legal research services. An Internet site probably will not provide enough archival (historical) coverage to allow comprehensive research on many topics or it may provide versions of the text of cases which are not authoritative. The search engines available may not be as sophisticated or as powerful as those available on subscription online legal research services. Citator services available on Bloomberg Law (BCite), Lexis (Shepard’s) and Westlaw (KeyCite) currently have no counterpart on the Internet.