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xxHash64 Hash Calculator: GB/s Throughput Dedup Online

xxHash64 hash calculator online: 64-bit hashes at GB/s speeds for ZFS deduplication and database hash tables, with instant hex output and verification.

Updated 2026-08-16

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Features

  • Compute xxHash64 checksums online: GB/s throughput for ZFS dedup and database hash tables
  • Real-time 64-bit hash computation with 16 hex character output
  • One-click copy, save as .txt, and uppercase/lowercase toggle
  • Powers ZFS storage deduplication and high-speed data synchronization
  • Hash verification against known xxHash64 checksums
  • WebAssembly implementation for high-speed hashing
  • Hash comparison tool: paste an expected 16-character xxHash64 value alongside new output for instant verification
  • Real-time input length counter: displays character and byte counts alongside the hash for reference
  • Compute xxHash64 hashes on any device without file system tools
  • Session history: retains previous xxHash64 results during the session for easy reference and comparison

How to Use

  1. 1Type or paste your text into the input box above.
  2. 2Your hash digest appears instantly; no page reload needed.
  3. 3Toggle UPPERCASE / lowercase to change the hex output format.
  4. 4Click the copy icon to copy the hash to clipboard, or use Save to save as .txt.
  5. 5Paste an expected hash into the Verify field to check for a match.
  6. 6How to use xxHash64 for ZFS-like deduplication: when designing storage systems, compute xxHash64 of each data block. Use the 16-character hash as a dedup key, but always follow matches with byte-level comparison to guarantee correctness.
  7. 7How to hash large datasets at RAM speed: xxHash64 achieves 15-20 GB/s on modern CPUs. Paste large text samples and observe how the 64-bit hash is computed in milliseconds, ideal for high-throughput data pipelines.
  8. 8How to compare xxHash64 with xxHash32 output: input the same text in both tools. xxHash64 produces 16-character hashes (vs xxHash32's 8 characters), providing dramatically lower collision probability for large datasets.
  9. 9How to use xxHash64 for data synchronization: when syncing files between systems, compute xxHash64 of each file chunk. Only transfer chunks whose hashes don't match the receiver's, saving bandwidth.
  10. 10How to generate consistent hashes for distributed systems: xxHash64 is deterministic across all platforms. Use it to compute consistent hash values for consistent hashing rings in distributed caching and load balancing.

Frequently Asked Questions

What is xxHash64?

xxHash64 is the 64-bit variant of the xxHash family, designed by Yann Collet. It produces 16-character hex hashes at nearly RAM-speed throughput (15-20 GB/s on modern CPUs). It is used for ZFS deduplication, high-performance database hash tables, and fast data synchronization.

How does ZFS use xxHash64?

ZFS uses xxHash64 for block-level deduplication checksums. When ZFS stores or reads data, it computes xxHash64 of each block to detect duplicates, enabling transparent data deduplication that can save terabytes of storage in VM and backup environments.

xxHash64 vs xxHash32: which should I use?

xxHash64 provides better collision resistance at similar speed on 64-bit CPUs. For hash tables with millions of entries, xxHash64 significantly reduces collision probability. Use xxHash32 for embedded/32-bit systems. Use xxHash64 for 64-bit servers and large datasets.

What is the real-world throughput of xxHash64?

On modern CPUs like Intel Core i9 or AMD Ryzen, xxHash64 can achieve 15-20 GB/s on a single core, far exceeding most storage and network speeds. This makes it practical for real-time hashing without becoming a bottleneck.

Is xxHash64 suitable for file deduplication?

Yes, with caveats. xxHash64 is extremely fast for identifying potential duplicates in large datasets. However, because it is non-cryptographic, collisions are possible (though very rare). For guaranteed deduplication, follow xxHash64 matches with byte-by-byte comparison.

How many characters does xxHash64 produce?

xxHash64 produces a 64-bit hash displayed as 16 hexadecimal characters, double xxHash32's output, providing 2^64 possible values (about 1.8 × 10^19).

What is the collision probability of xxHash64?

With 64-bit output, collision probability is extremely low. Even with 1 billion entries, the chance of at least one collision is only about 2.7%. For virtually all practical applications, collisions can be safely ignored.

Can xxHash64 be used for cryptographic purposes?

No. xxHash64 is explicitly non-cryptographic. It provides zero collision resistance against intentional attacks and zero preimage resistance. Use SHA-256, BLAKE2, or SHA-3 for any security-sensitive application.

What databases and storage systems use xxHash64?

ZFS uses xxHash64 for deduplication. RocksDB and LevelDB use xxHash for block checksums. Kafka uses xxHash for record batch checksums. Many object storage systems use xxHash64 for fast integrity verification.

Is xxHash64 faster than MD5?

Yes, significantly. xxHash64 is approximately 5-10x faster than MD5 on modern CPUs while providing a 64-bit output (vs MD5's 128-bit). For non-cryptographic integrity checks, xxHash64 outperforms MD5 substantially.

Does xxHash64 support streaming?

Yes, xxHash64 supports streaming/incremental computation through its stateful API. This allows hashing of arbitrarily large data without loading it all into memory.

What is the difference between xxHash64 and CityHash64?

Both are fast non-cryptographic hashes. xxHash64 is generally faster with better cross-platform consistency. CityHash64 is optimized for short keys on x86-64. xxHash64 has simpler code and broader platform support.

Why does my xxHash64 hash change after moving a file between Windows and Linux?

The bytes changed, not the hash: text files often get line-ending conversions (CRLF to LF) on transfer, some editors add a trailing newline or BOM, and file managers or archives can rewrite metadata. Hash the file before and after on each side and compare the hex; identical bytes always give the identical xxHash64. For safe transfer, zip the file (which keeps bytes intact) or copy in binary mode and hash the copy on the destination.

Why does my xxHash64 hash differ from other tools or websites?

Hash output depends on the exact input bytes, and the usual culprits are invisible differences: UTF-8 vs UTF-16 encoding (common when pasting from Windows apps), a trailing newline added by some editors or echo commands, a byte-order mark at the start, or a leading/trailing space. Also verify the algorithm and its variant (SHA-512 vs SHA-384, Keccak vs SHA3, BLAKE2b vs BLAKE3), since they produce different digests for the same input. This tool hashes the exact text you paste; compare like for like.

Why shouldn't I use xxHash64 for password hashing?

xxHash64 is a fast non-cryptographic hash with no salt and no work factor: an attacker can compute it millions of times per second and identical passwords produce identical hashes, so brute-force and rainbow tables are trivial. Passwords need slow, salted, memory-hard hashes like bcrypt, Argon2, or scrypt. Use xxHash64 for integrity checks and deduplication, never for storing passwords.