checksum is a lightning-fast simple-to-use, no-nonsense SHA1 & MD5 hashing utility for Windows, capable of creating & verifying checksums of files and folders, even whole drives, with just one or two clicks. checksum is robust, lightning fast, intuitive, and completely customizable; comes with a customizable installer, or alternatively, can be simply unzipped for 100% portable operation. Or both. Features: True point-and-click hash creation and verification, choice of MD5 or SHA1 hashing algorithms, effortless recursion (through an entire volume, if you wish), user-defined file mask groups (e.g. hash only movie files), automatic music playlist creation (m3u or pls), automatic checksum synchronization, integrated Explorer context (right-click) operation, true mix-and-match MD5 & SHA1 handling (even in the same file!), extensionless & invisible checksum file support, intelligent checksum file naming with dynamic tokens, supports hashing read-only volumes with configurable fall-back, extensive logging capabilities, with intelligent log handling and dynamic log naming in plain text or XHTML+CSS, log append and auto log-rotation, drag & drop support, effortless legacy and *nix MD5/SHA1 file handling, optional *everything*, including one-file 'root' checksums, individual or folder hashes, UPPER/lowercase hashes, UTF-8 or ASCII output, dynamic ToolTip style progress, audio alerts, UNIX or Windows relative or absolute paths, ignore file types, 'quiet' operation (for scripters), and more! If you hold down the SHIFT key when you launch checksum, you get its one-shot options dialog, where you can tailor your settings, on-the-fly, for any special jobs. checksum is simply the fastest, most intuitive, most intelligent hashing utility in the world. Try it! checksum was also the world's first 'Shirtware' application - you can use it for FREE, or else pay for it by buying something you need anyway!