A WARC file is an archive that contains information about a website that was gathered from "crawls" performed by Internet bots for archival purposes. It stores WARC records, which may include information about the HTML, CSS, images, video, and scripts used by websites. WARC files also include metadata about how and where the web information was retrieved.

The Web ARChive (WARC) format was developed as an improvement upon the Internet Archive .ARC format for the purpose of archiving information on the web. One of the WARC format improvements is the support of capturing metadata about the archiving process. The WARC format is widely considered a standard for archiving and documenting information on the web by library systems. It may also be used by web developers for archiving design trends to reference in the future. NOTE: WARC files compressed with gzip compression appear as .warc.gz files.