File Checksum

The File Checksum calculator produces five integrity fingerprints for any file — CRC32, MD5, SHA-1, SHA-256, and SHA-512 — without uploading a single byte. Drop a file onto the zone and the tool computes CRC32 with its own hand-written 256-entry lookup table, then runs the SHA family through the Web Crypto API. MD5 is attempted too, but since it is not part of the Web Crypto specification most browsers reject it, and the row honestly reports "MD5 not supported in this browser" rather than faking a value. Every result carries a copy button and a compute-time badge in milliseconds; a file info card shows the name, exact byte count, readable size, and detected MIME type. Recompute re-runs the batch, and Download report exports a text file with metadata and all checksums. Files over 500 MB are blocked to protect memory, with an amber pause warning above 50 MB. The notes section is refreshingly straight about security: CRC32 catches accidental corruption, SHA-1 is cryptographically broken, and SHA-256 or SHA-512 should anchor any real verification. For release managers and careful downloaders alike, this CRC32 MD5 SHA-256 checksum utility is the local, no-account way to verify file integrity.

1. 1

   Drag a file onto the drop zone or click "Choose a file".

2. 2

   Wait for the "Computing…" state — CRC32 and the SHA hashes run in sequence.

3. 3

   Read the five rows under the Checksums card, each with a Copy button.

4. 4

   Click "Recompute" to re-run on the same file, or "Download report" to export everything.

5. 5

   Check the File info card for size, readable size, and detected type.

• Verifying a downloaded firmware image against the vendor's published SHA-256.
• Confirming backup integrity before deleting the source copy.
• Publishing CRC32 and SHA-256 sums in release notes for an open-source project.
• Detecting accidental corruption in files copied between network shares.
• Comparing hashes across a delivery to prove two parties received the same file.
• Generating checksum reports for compliance archives that require them.

• Trust SHA-256 or SHA-512 for security decisions; use CRC32 for corruption only.
• Treat the MD5 row as informational — expect it to read unsupported in most browsers.
• Download the report when hashes must accompany the file itself.
• Compare against checksums published by the vendor, not ones you generated earlier.
• Keep files under 500 MB; above 50 MB, expect a brief UI pause.

• Copy any checksum with its per-row Copy button.
• The ms badges reveal CRC32's speed advantage over the SHA family.
• Reports are named <filename>-checksums.txt for easy archiving.
• Recompute after every download to confirm the file on disk matches the report.