CRC checksum

Compute CRC-32, CRC-16-CCITT, and Adler-32 of text or a file — the checksums older formats actually use.

Computed in this browser. Nothing is sent anywhere.

CRC-32 (IEEE 802.3, the zip/png variant), CRC-16-CCITT (init 0xFFFF), and Adler-32. Hex output is zero-padded. File mode hashes the raw bytes; text mode encodes as UTF-8 first.

How to use

  1. Paste text or drop a file.
  2. Run the checksum.
  3. Read the CRC-32, CRC-16-CCITT and Adler-32 report.

What it supports

CRC-32/ISO-HDLC (ZIP/PNG), CRC-16-CCITT (init 0xFFFF), and Adler-32 — all three are reported together. Text up to 2 MB, files up to 256 MiB. CRCs detect accidents, not tampering — use SHA-256 for integrity.

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