Md5Checker is a free, faster, lightweight and easy-to-use tool to manage, calculate and verify MD5 checksum of multiple files/folders Calculate and display MD5 checksum of multiple files at one time. Use MD5 checksum to fleetly verify whether files have been changed. Load, save, add, remove and update MD5 checksum conveniently. It is about 300 KB and does not require any installation (portable). What is MD5 checksum? MD5 checksum (MD5 hash) is a type of digests of files. It will become totally different if any modification has been made to the file, even a byte.