CRC32 checksum

CRC32 treats the input bytes as the coefficients of a large polynomial and divides them by a fixed generator polynomial; the 32-bit remainder is the checksum. The IEEE variant used here reflects the bits, uses the polynomial 0xEDB88320, and XORs the running value with 0xFFFFFFFF at the start and end.

The result is a single 32-bit number, conventionally written as eight hex digits. The same input always produces the same checksum, and a single flipped bit produces a very different one — which is exactly what makes it useful for spotting corruption.

Use CRC32 for cheap, fast detection of accidental errors:

• Verifying a file format chunk — matching the CRC stored in a PNG or zip entry.
• Detecting transmission corruption in embedded or serial protocols.
• Quick change detection where a short, non-secure fingerprint is enough.

Do not use it where an attacker could tamper with the data — for that you need a cryptographic hash like SHA-256.

1. Paste or type the text you want to checksum into the input box.
2. Read the CRC32 in three formats: uppercase hex, 0x-prefixed hex, and unsigned decimal.
3. Copy whichever form your target system expects with its Copy button, or press ⌘/Ctrl+Enter for the hex.

• Wrong variant. CRC32C (Castagnoli) and CRC32 (IEEE) give different results. This tool computes the IEEE variant used by zip, gzip, and PNG.
• Encoding mismatch. The checksum is over UTF-8 bytes. If another tool hashes Latin-1 or raw binary, the numbers will not match even for the same visible text.
• Signed vs unsigned. Some languages report CRC32 as a signed integer. This tool shows the unsigned value; convert if your environment expects a signed one.

The checksum is calculated entirely in your browser from the bytes of your input. No text is uploaded, stored, or logged, so you can fingerprint sensitive strings without them leaving the tab. Everything is discarded when you navigate away.