File Checksum Calculator
Compute the SHA-256, SHA-1, SHA-384, or SHA-512 checksum of any local file, with its size. Your file is processed locally and never uploaded.
Input
Your file is processed entirely in your local browser and is never uploaded to any server.
How it works
- The selected file is read into memory with
FileReader/arrayBuffer()and hashed withcrypto.subtle.digest. - Each algorithm produces a fixed-length digest regardless of file size — 160 bits for SHA-1, 256/384/512 bits for the SHA-2 family.
- The checksum is shown in hexadecimal, which is the format used by most download pages and package managers.
- Hashing runs in your browser only; the file never leaves your machine.
About File Checksum Calculator
A checksum (or file hash) is a short fingerprint that changes drastically when even a single bit of the file changes. Its main uses are verifying that a downloaded file matches the publisher's official copy, detecting accidental corruption during transfer or storage, and deduplicating identical files. SHA-256 is the current recommendation — it is fast, universally supported, and collision-resistant — while SHA-1 is considered broken for security purposes and should only be used to match checksums published long ago.
Use this tool whenever you download a binary, a firmware image, or an installer and want to confirm it was transferred intact. Keep in mind that a checksum only proves the file matches the value it was compared against; it does not prove the file is safe. A malicious actor who controls the download can simply publish a matching checksum — for real protection against tampering, verify cryptographically signed hashes from a trusted source (for example, GPG signatures or HTTPS package registries).