File SHA-256 Checksum Tool
Calculate and verify the file's SHA-256 checksum to ensure it hasn't been altered or corrupted. You can also generate checksums when sharing your files, so recipients can verify authenticity. Files are processed locally in your browser, not uploaded. This cryptographic hash function produces a unique 256-bit (32-byte) hash value for a given file, making it a reliable method for verifying data.
Processing large files may take some time. For example, a 3GB file can take a minute or more to process, depending on your device. Processing time grows linearly with file size. Further details...
It's WASM, It's Fast
This page uses the WASM technique, which is faster than the same JavaScript code for computing the SHA256 hash. Modern browsers have the CryptoAPI set of functions that are faster than WASM, but they lack streaming processing capabilities. This means the file must be fully loaded into the browser's memory before processing, which can be a problem for large files. Therefore, the WASM option seems to be the best choice for computing the SHA256 hash of files of different sizes in web applications.
Here are the results of performance tests for obtaining the SHA256 hash of a 100MB (104,857,600 bytes) file.
| Method | ms | bytes per ms | |
|---|---|---|---|
| Windows 11, Intel Core i7-10700 CPU 2.90GHz (Desktop, 2020) | |||
| Edge CryptoAPI | 465 | 225,500 | |
| Edge WASM | 740 | 141,700 | |
| Edge Javascript | 7,475 | 14,000 | |
| Firefox CryptoAPI | 683 | 153,500 | |
| Firefox WASM | 980 | 107,000 | |
| Firefox JavaScript | 4,950 | 21,180 | |
| Powershell | 302 | 347,200 | |
| VM Linux Mint | 385 | 272,350 | |
| WSL Ubuntu | 872 | 120,250 | |
| Windows 11, AMD Ryzen 9 7940HS 4.00 GHz (Mobile, 2023) | |||
| Edge WASM | 540 | 194,100 | |
| Edge Javascript | 4,760 | 22,000 | |
| Powershell | 104 | 1,008,245 | |
| Android 14, Samsung Exynos 2400e 3.11 GHz (Phone, 2024) | |||
| Firefox WASM | 1210 | 86,659 | |
| Chrome WASM | 2400 | 43,690 | |
You can use the command line to get the SHA256 checksum.
Linux:
sha256sum <your_file>
Mac:
shasum -a 256 <your_file>
Windows Powershell:
Replace <your_file> with the path and name of the file you want to hash. Use quotes if the path or file name contains spaces.
Trivia
• The hash of an empty file is
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.
Though it may seem useless, it serves as a reference point in hashing algorithms.
• You can add the expected URL parameter when linking to this page.
• In theory, because SHA-256 produces a fixed-size output of 256 bits, there are 2256 possible hash values. However, the input space is effectively infinite, so collisions must exist. While no two distinct files have been found to produce the same SHA-256 hash as of now, and the algorithm is considered secure against known collision attacks, it is still theoretically possible for two different inputs to hash to the same output.