About this tool
Drag in any file to compute its CRC-32 and Adler-32 checksums using a hand-written WebAssembly module, plus a SHA-256 hash via Web Crypto. Files are streamed and never uploaded — ideal for verifying downloads stayed intact.
Frequently asked questions
Why WebAssembly?
The CRC-32 and Adler-32 loops run in compiled WebAssembly, which is markedly faster than plain JavaScript on large files. A JavaScript fallback runs if WASM is unavailable.
Is my file uploaded?
No. The file is read and hashed in a stream entirely inside your browser; nothing is sent to any server.