File to CRC32.

CRC32 is a 32-bit cyclic redundancy check: the remainder of the input, treated as a polynomial, divided by a fixed 33-bit polynomial. The form everyone means by CRC32 uses the IEEE 802.3 polynomial 0x04C11DB7 and is what ZIP, gzip, PNG, Ethernet and zlib.crc32 compute; that is what this tool gives.

Every single-bit error, every odd number of bit errors, any two or three flipped bits in a message up to about 11 KB, and any burst of up to 32 bits: that is what the polynomial guarantees. For a random corruption of any size the chance of a false pass is one in four billion.

No. A CRC is linear: given any file, anyone can append four bytes to make it match any CRC they like, and a change that keeps the checksum is easy to craft. It detects accidents (a flipped bit, a truncated download, a bad sector), which is all it was made for. Against a person, use SHA-256 or BLAKE3.

ZIP entries and gzip members end in one; every PNG chunk carries one; Ethernet frames, SATA, MPEG-2 and Bluetooth packets use CRC-32 variants; and with the SSE4.2 and ARMv8 instructions a different polynomial (CRC-32C, Castagnoli) runs at memory speed in iSCSI, ext4 and Btrfs. Those variants give different numbers from this one.

Faster than any cryptographic hash, several gigabytes a second with hardware help, since it is a table lookup per byte with no mixing rounds. xxHash is about as fast with better distribution for hash tables; CRC32 is the one with error-detection guarantees and the one existing formats expect.

Nothing leaves your browser. The file is read on your machine and hashed there, by the browser's Web Crypto API or a WebAssembly build of CRC32 loaded on first use; the page makes no request with its bytes. You can load the page, go offline and keep hashing.

Drop the file onto the pane or choose it with the button. It is read into memory and hashed at once, with no size steps and no upload progress because there is no upload. Files up to 1 GB work; a 100 MB file takes well under a second on CRC32.

Paste the checksum the publisher gave you into the Verify field, in hex of either case, with or without spaces, colons or a 0x prefix, or in Base64. The tool says whether it matches the file you dropped. A match means the bytes are exactly the ones that were published.

Hex by default, 8 characters; Base64 and Base64url are one click away and re-encode the same 4 bytes. The download button saves a line in the `checksum filename` form that sha256sum-style tools read.

No. The "File to CRC32" tool is free and opens without a sign-in, an account or an install.

Nothing. The "File to CRC32" tool holds your input in the page's memory, so closing or reloading the tab clears it, and it saves nothing in this browser.

The toolbar switches to CRC64 and Adler-32 without leaving the page. Each one reads the same input, so you can compare digests side by side.

CRC32 is computed by a WebAssembly build from the hash-wasm library, which the page loads the first time you hash something and reuses after that.

No: CRC32 is a checksum or fast non-cryptographic hash, and none of the algorithms in this toolbar take a key, because a keyed checksum proves nothing.

Yes: the CRC32 hash generator page has the same algorithms and options and opens on the text box. This page opens on the file pane.

Not on its own. CRC32 is built to be fast, and fast hashes are cheap for an attacker to guess against. Passwords need a salted, deliberately slow hash: use Argon2id, Argon2d, and bcrypt from the hash generators, which draw a fresh random salt each time.

Closest to the "File to CRC32" tool: CRC32 hash generator, CRC64 hash generator, Adler-32 hash generator, xxHash32 hash generator. Each opens on its own page, free and in the browser.

The "File to CRC32" tool is one of 64 in its group. The group's page, /tools/hash, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.