File Checksum Tool is a free Windows utility that computes and verifies checksums for your files. A checksum, or hash, is a short fingerprint calculated from a file's contents: change a single byte and the hash changes completely, so comparing a file's hash with the value its source published is a quick, reliable way to confirm the file arrived intact. The one-step check is the point. Paste the hash from a download page and pick your file; it detects the algorithm for you and shows a plain green Match or red No match. Or verify a whole checksum file - SHA256SUMS, .sha256, .md5, .sfv, BSD-tagged, xxhsum, even PGP clear-signed ones - and every entry is marked OK, FAILED or missing. Add as many files and folders as you like; each file is read once for all the algorithms you have selected, and large files hash in the background with progress and Cancel. It computes MD5, SHA-1, the SHA-2 and SHA-3 families, BLAKE3, CRC32 and xxHash, plus legacy MD2 and MD4. It also shows a file's digital signature and the address it was downloaded from when Windows recorded one, and can look any file up on VirusTotal by its hash. Save results as sha256sum, BSD, SFV, CSV or JSON, hash typed text, and verify straight from the Explorer right-click menu. A command-line tool, fchash, is included for scripting. File Checksum Tool runs on Windows 7 SP1 through Windows 11, as 32-bit, 64-bit and ARM64 programs, and the application and setup are code-signed. It is free to download and use, for files on a computer you control.