SHA256 OnlineCheck accidental transfer errors
Compare a CRC-32/ISO-HDLC reference for a copied payload. CRC32 is not authentication.
CRC-32/ISO-HDLC · error detection · Files
CRC32 File Checksum
Calculate CRC32 for one or many files. Verify a GNU or BSD checksum list without uploading files.
Input No upload
or drop files here · up to 100 · 2 GiB eachFiles stay on this device.
Output Your result · CRC32
Ready to calculate
0 / 0 bytes processed
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. |
Verify CRC32 files in three steps
- 1
Select the actual files
Choose up to 100 files, each at most 2 GiB. The file contents are read locally.
- 2
Read the calculated checksum
CRC32 returns 8 lowercase hex characters. Copy digest preserves the whole output.
- 3
Compare a trusted release list
Read a local manifest or paste a trusted expected value. Review each filename and any missing entries.
CRC32 file workflows
Check the right archive bytes
An archive-entry CRC concerns entry contents, while selecting the archive here checks the container file.
Keep CRC variants separate
Do not compare a CRC32C/Castagnoli reference with this CRC-32/ISO-HDLC output.
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.
Verify CRC32 files
Choose or drop files and calculation starts automatically. Each file is read sequentially in 2 MiB chunks inside a background worker. Up to 100 files and 2 GiB per file are accepted. Cancel terminates the active worker.
Paste a trusted expected digest to compare directly. With no expected value, Not compared yet is not a verification success. Every batch row includes the complete digest, byte count and comparison outcome.
Read a CRC32 checksum manifest
Open manifest options to read a local list or paste GNU digest–filename lines or BSD ALGORITHM (filename) = digest lines. Verify selected files runs the comparison again with the list. The filename is matched exactly, including spaces and relative folders.
Duplicate names, invalid digest lengths, mixed algorithms and unsupported lines block manifest verification. Missing files and files not listed are displayed; no basename-only guessing or silent success is used. Lists are limited to 1 MiB and 100 entries.
Private file handling and practical limits
Hashing runs in browser memory with no upload endpoint. Microsoft Clarity runs on this page, with the entire tool workspace masked, including filenames, digests and manifests. Google Analytics runs only on the four information pages. A local report can be copied or downloaded. See Privacy for details.
The 2 GiB ceiling is not a promise about every phone. If a device struggles, cancel and use a system checksum utility. A matching value proves only equality with the reference digest, not safety or publisher identity.
Known CRC32 result: empty input
CRC32 · 0 bytes · no HMAC. Empty input is not the same as no file selected.
00000000CRC32 file checksum FAQ
Can CRC32 prove a file was not maliciously modified?
No. CRC32 is designed to detect accidental errors and is easy to forge. It is not a substitute for a trusted cryptographic hash or digital signature.
Why does my archive entry CRC not match the archive file?
An archive entry CRC normally concerns that entry’s uncompressed contents. This tool hashes the exact bytes of the selected file, so selecting the archive checks the container instead.
Is a CRC32C download reference supported?
No. This tool implements CRC-32/ISO-HDLC, not CRC32C. Check the variant named by the source before comparing an eight-character value.
Does CRC32 include file metadata?
No. It reads the selected file’s raw contents only. Renaming a file does not change CRC32, but manifest matching still requires the listed filename.
What happens after selecting files for CRC32?
Files are hashed automatically and sequentially. The result says calculated until an expected digest is supplied; Match or Mismatch describes a comparison, not just a completed calculation.
How should I prepare a CRC32 checksum manifest?
Use GNU digest followed by a filename, or a BSD algorithm (filename) = digest line. Each CRC32 reference needs 8 hex characters. Malformed lines and duplicate names block verification.
Why is a file missing from my CRC32 batch?
Names must match exactly, including spaces and relative paths. A selected file not in the manifest is reported separately and is not silently treated as a verified match.
Can I export my CRC32 batch results?
Download report saves a local text report with filenames, byte counts, digests and comparison states. Keep that report private if its filenames or checksums are sensitive. No report is uploaded.