xxHash128 (XXH128) is xxHash3's 128-bit output: the same 2019 algorithm by Yann Collet producing 16 bytes, 32 hex characters, for uses where a 64-bit value would eventually collide by chance. On long inputs it costs almost nothing over the 64-bit form.

No, and it does not try to be. xxHash is a non-cryptographic hash: it has excellent distribution and passes the SMHasher test suite, but anyone who knows the algorithm can make two inputs collide. Use it for hash tables, checksums and deduplication; use SHA-256 or BLAKE3 when an attacker might choose the input.

Why 128 bits for a non-cryptographic hash?

By the birthday bound, a 64-bit hash sees a random collision after about four billion items, which a large deduplication index or content store can reach; at 128 bits the expected count is 18 quintillion, which it cannot. That is the whole case for the longer output.

What seed does the tool use?

The tool uses seed 0, the reference implementation's default and what xxhsum prints. A different seed gives a completely different hash, which is how a hash table can defend against crafted collisions; if a system you compare against seeds its xxHash, its values will not match these.

Where is xxHash128 used?

Deduplication and content-addressed storage of trusted data, distributed hash tables, change detection across very large datasets, and as a cheaper MD5 replacement where nobody can choose the inputs. Where an attacker could, use BLAKE3 or SHA-256 instead.

Is my text or file uploaded anywhere?

Nothing leaves your browser. The hash is computed on your machine, by the browser's Web Crypto API or a WebAssembly build of the algorithm loaded on first use, and the page makes no request with your input. You can load the page, go offline and keep hashing.

How do I get the xxHash128 of a file?

Drop the file onto the input or choose it with the button, and the tool reads it in your browser and hashes the bytes. Files up to 1 GB work; past that the browser would need the whole file in memory, so the tool declines. Paste the published checksum into the Verify field to compare.

Hex, Base64 or Base64url: which should I use?

Hex is the common form: 32 characters from 0 to 9 and a to f, the same value in upper or lower case. Base64 writes the same 16 bytes in fewer characters, and Base64url swaps + and / for - and _ with no padding. Switch the output and the checksum is re-encoded, not recomputed.

Why does my checksum differ from the command line?

Text is hashed as UTF-8 bytes, which is what every language and command line does by default. A trailing newline changes the checksum, so `echo -n` or this tool's input, with no newline added, matches a command-line tool run on a file without one.

xxHash128 hash generator.

Paste text or drop a file and read its xxHash128 (XXH128) hash as you type. xxHash128 is xxHash3's 128-bit output, for deduplication and content stores where 64 bits would eventually collide; everything runs in your browser and nothing is uploaded.128 bits32 hex characters2019 published0 bytes uploaded

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How it works

4 steps, no account. It runs in your browser and nothing is uploaded.

Enter text or a file
Type or paste anything, or drop a file onto the input. The checksum updates with every keystroke.
Pick the algorithm and format
xxHash128 is the default; switch to xxHash32, xxHash64 and xxHash3, and read the checksum as hex or Base64.
Pick the format
Read the checksum as hex in either case, or as Base64 or Base64url; the value is re-encoded, not recomputed.
Verify, copy or download
Paste a published checksum to confirm a download, or copy and download your own.

Checksums and fast hashes

xxHash is speed without security. Hash tables, checksums, deduplication: anywhere nobody is trying to make two inputs collide.

CRC32
32 bits, 1961. A polynomial division: catches every one-bit and most burst errors, trivially forged on purpose. ZIP, gzip, PNG, Ethernet.
CRC64
64 bits. The same arithmetic with a longer polynomial, for large files and storage. The ECMA-182 form here: xz, Redis, Go's crc64.ECMA.
Adler-32
32 bits, 1995. Two running sums modulo 65,521; faster than CRC32 and weaker on short input. The zlib trailer, so inside every PNG.
xxHash32
32 bits, 2012. A non-cryptographic hash, not a CRC: good distribution for hash tables, several GB/s. LZ4 frame checksums.
xxHash64
64 bits, 2014. The 64-bit variant: fewer accidental collisions at the same speed on a 64-bit CPU. Zstandard, rsync 3.2.
xxHash3
64 bits, 2019. XXH3: the redesign for SIMD, fast on short keys too. The xxHash to pick for anything new.
xxHash128
128 bits, 2019. XXH3's 128-bit output, for deduplication and content addressing where 64 bits is too few.
MD5
128 bits, broken as a cryptographic hash and slower than every hash above. Only its ubiquity keeps it as a checksum.

Nearby in the hash generators. Every one free, in the browser.

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Complete multi-page sites you can ship as they are.Templates: All 14 templates
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xxHash128 hash generator.