It is a checksum, often loosely called a hash. It reliably detects accidental errors — every single-bit error and every burst up to 32 bits — but it has no resistance to deliberate tampering. Use SHA-256 when someone might alter the data on purpose.

CRC32 Checksum Generator

Q: Is my text or file uploaded anywhere?

No. The CRC-32 digest is computed by JavaScript in this tab, and an imported file is read locally with the browser's File API. Nothing leaves your machine, which is why it is safe to hash configuration files or internal data here.

Q: Why does another tool give me a different CRC-32 for the same text?

Because the bytes differ, even if the text looks identical. The usual culprits are a trailing newline (most command-line tools add one when you echo), CRLF versus LF line endings, a byte-order mark, or a different text encoding. This tool hashes exactly what is in the box, encoded as UTF-8, and points out line endings and BOMs when it sees them.

Q: Why do different tools give different CRC-32 values?

There are several 32-bit CRCs with different polynomials and settings — CRC-32C (Castagnoli), used by iSCSI and ext4, is the common alternative. This tool computes the IEEE variant used by ZIP and PNG, whose check value for 123456789 is cbf43926.

Q: Can two files have the same CRC-32?

Easily. There are only about 4.3 billion possible values, so collisions appear by chance after around 77,000 random files, and they can be produced on purpose instantly.

Calculate the CRC-32 checksum of text or files in your browser — the checksum ZIP, PNG and Ethernet use.

Text to hash (0 bytes)

Output Hash each line separately

Digest

Compare against a published checksum (optional)

What It Does

This tool calculates the CRC-32 checksum of text or a file — the IEEE 802.3 variant used by ZIP, gzip, PNG and Ethernet. A CRC is polynomial division over the bits of your data, and it is excellent at catching accidental damage such as burst errors. It is not a cryptographic hash: anyone can adjust data to hit any CRC value, so the page shows the result as a checksum, not a security fingerprint.

When to Use It

You are checking the CRC-32 stored in a ZIP or gzip header against the file's contents.
A firmware or embedded protocol appends a CRC-32 and you need to compute the expected value.
You want a fast 32-bit fingerprint for detecting accidental changes in a cache.
You are debugging a PNG chunk and need the CRC of its type and data.

Worked Examples

123456789

Gives cbf43926 — the standard check value for CRC-32. Any correct CRC-32/ISO-HDLC implementation must produce it.

The CRC-32 of nothing is 00000000.

IEND

Gives ae426082 — the CRC every PNG file ends with, because the final IEND chunk has no data.

Features

CRC-32 digest as you type

Hash files as raw bytes without uploading

Hex / HEX / Base64 output

Hash each line separately

Checksum comparison that recognises the wrong algorithm

Warnings for line endings

BOMs and passwords

How to Use

1. Type or paste text, or choose Hash a file to hash a file's raw bytes. 2. Pick the output encoding the value will be compared against — hex is the usual one. 3. To check a published checksum, paste it into the comparison box; the tool tells you whether it matches and, if not, whether it is even the same algorithm.

Common Mistakes

Hashing text that is not byte-for-byte what the other side hashed. A trailing newline, Windows line endings or a byte-order mark each produce a completely different CRC-32 value, and none of them are visible.
Comparing a hex digest with a Base64 one. They encode the same bytes differently, so they never look alike even when they match — switch the output format before deciding two values disagree.
Comparing digests in mixed case and concluding they differ. Hex is case-insensitive; ABCDEF and abcdef are the same value.
Using a plain CRC-32 digest where a secret is involved. To prove a message came from someone holding a key, you need HMAC, not hash(secret + message).

Frequently Asked Questions

Is my text or file uploaded anywhere?

Why does another tool give me a different CRC-32 for the same text?

Is CRC32 a hash?

Why do different tools give different CRC-32 values?

Can two files have the same CRC-32?

Everything runs in your browser. Text and files are hashed locally — nothing is uploaded, logged or stored.