SHA256 OnlineDiagnose accidental changes
Compare an existing CRC-32/ISO-HDLC reference for a copied payload.
CRC-32/ISO-HDLC · error detection · Text
CRC32 Calculator
Calculate CRC32 from UTF-8, Hex or Base64 text. Compare a trusted expected digest locally.
Input No upload
Output Your result · CRC32
CRC32 calculated
0 decoded bytes · UTF-8 · input changes update automatically
Browser-local hashing. Inputs masked in Clarity.
No account. No uploads. Just your browser.
CRC32 versus SHA256
| Algorithm | What differs |
|---|---|
| CRC32 | 32-bit accidental-error checksum; not cryptographic. |
| SHA256 | 256-bit cryptographic hash; still needs a trusted reference for verification. |
Generate CRC32 from exact bytes
- 1
Enter or decode your message
Start empty, paste UTF-8 text, or choose Hex or Base64 for encoded bytes.
- 2
Inspect the full digest
CRC32 returns 8 lowercase hex characters. Copy digest preserves the whole output.
- 3
Compare or reproduce a keyed result
Paste an expected value for comparison. CRC32 has no HMAC mode.
CRC32 text workflows
Check a known CRC variant
Use the 123456789 check string to distinguish CRC32 from other CRC families.
Choose a security-appropriate check
Use the publisher’s cryptographic digest for adversarial integrity checks; CRC32 is not authentication.
Details that affect your CRC32 result
How CRC32 works
This calculator uses CRC-32/ISO-HDLC, also called CRC-32/IEEE: polynomial 0x04C11DB7, reflected input/output, initial and final XOR 0xffffffff. The result is eight hexadecimal characters. It is not CRC-32C.
CRC32 detects accidental changes; it is not a cryptographic hash, a signature, or an authentication method. HMAC is intentionally unavailable for CRC32. The standard check string 123456789 yields cbf43926.
Generate a CRC32 hash from exact bytes
Type or paste text for an automatic result. UTF-8 preserves whitespace and line endings. Hex accepts pairs of digits with optional whitespace; Base64 requires the standard padded alphabet. Invalid encoding stops calculation instead of hashing a different input.
The default result is the digest of zero bytes. The abc example contains exactly 61 62 63 in hex with no newline. Adding Enter changes the bytes and therefore the result.
Compare a value or use a key
Paste a complete hexadecimal expected value to see Match or Mismatch. Outer whitespace and uppercase hex are accepted; incomplete digests, filenames and embedded spaces are not.
CRC32 has no HMAC option.
Switch to files without changing the algorithm
The CRC32 file checksum tool reads raw bytes in chunks and supports batch manifests. Text mode is limited to 8 MiB decoded input; use file mode for larger data.
No input is uploaded. Only a light/dark theme preference is stored. Copy and report downloads remain on your device.
Known CRC32 result: empty input
CRC32 · 0 bytes · no HMAC. Empty input is not the same as no file selected.
00000000CRC32 hash generator FAQ
Which CRC32 variant is implemented?
This page uses CRC-32/ISO-HDLC, also commonly called IEEE CRC32. The ASCII check string 123456789 returns cbf43926.
Can I calculate CRC32C here?
No. CRC32C/Castagnoli uses a different polynomial. It is not interchangeable with CRC-32/ISO-HDLC, even though both outputs have eight hex characters.
Why is there no Use HMAC checkbox for CRC32?
CRC32 is not a cryptographic hash and is not supported by this tool’s HMAC construction. Choose a supported cryptographic hash when your protocol requires HMAC.
Is the output decimal or hexadecimal?
The result is eight lowercase hexadecimal characters, including leading zeroes. Convert a decimal reference separately before comparing; do not paste its decimal digits as if they were hex.
How do I hash encoded bytes with CRC32?
UTF-8 hashes literal text. Hex and standard padded Base64 decode to bytes first. abc, Hex 616263 and Base64 YWJj represent the same bytes; invalid encodings stop calculation.
Will spaces or Enter change my CRC32?
Yes. Text is not trimmed. A trailing newline, carriage return, byte-order mark or extra space changes the byte sequence and usually the result.
How do I compare a CRC32 expected value?
Paste exactly 8 hexadecimal characters. Uppercase and outer whitespace are accepted. Match means equality with your reference, not proof of a trustworthy source.
Where does this CRC32 generator store my input?
Text and keys stay in browser memory, not URLs or localStorage. The tool saves only your theme preference; Clarity may use its own identifiers, as explained in Privacy. Text mode accepts up to 8 MiB of decoded bytes; use file mode for larger inputs.