Austin Appleby · hash tables · bloom filters

MurmurHash

MurmurHash3 — fast, well-distributed non-cryptographic hash. Excellent avalanche and low collision rate. Used in Apache Cassandra, Hadoop, nginx, and many bloom filter libraries. Pure JavaScript.

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MurmurHash
 

How to use this tool

  1. Choose a variant with the tabs — MurmurHash3 32-bit, MurmurHash3 128-bit (x86), or MurmurHash3 128-bit (x64).
  2. Type or paste text into the Input text box — the hash appears instantly in the MurmurHash display.
  3. Hit Copy to grab the hash to your clipboard.
  4. Switch tabs to recompute the same input under a different variant and compare the outputs.
  5. Use Clear any time to reset the input and start over.

Why this tool is helpful

Hash tables & key distribution

MurmurHash3's even, well-distributed output makes it a go-to for hash tables, sharding, and consistent key placement.

Bloom filters & sketches

Fast, non-cryptographic hashes are the engine behind probabilistic data structures like bloom filters and HyperLogLog.

Verify library output

Check that your code matches reference implementations used by Apache Cassandra, Hadoop, and nginx — no build required.

Compare variants

32-bit returns 4 bytes (8 hex digits); the 128-bit variants return 16 bytes (32 hex digits). See both side by side.

Spot collision-prone hashing

Strong avalanche means a one-character change flips roughly half the output bits — a quick sanity check for weak hashes.

Stay private

Everything runs in your browser. Nothing is uploaded, logged, or sent to a server — safe for sensitive keys and payloads.

FAQ

What is MurmurHash3?

MurmurHash3 is a fast, non-cryptographic hash function by Austin Appleby, designed for speed and good distribution rather than security. It maps arbitrary input to a fixed-size hash.

Is MurmurHash3 a cryptographic hash?

No. Don't use it for passwords, MACs, or digital signatures — it isn't resistant to adversarial collisions. For security, use SHA-256 or similar.

What's the difference between the 32-bit and 128-bit variants?

The 32-bit variant outputs 4 bytes (8 hex digits). The 128-bit variants output 16 bytes (32 hex digits). The x86 and x64 128-bit versions use different internal layouts, so they produce different hashes.

Why is the seed fixed at 0?

A fixed seed keeps results deterministic and reproducible: the same input and variant always produce the same hash, matching other tools that use seed 0.

Can I hash Unicode or emoji?

Yes — you can hash any text. The hash is computed from the characters exactly as entered, so the same input and variant always yield the same result.

Why does the hash change completely when I edit one character?

MurmurHash3 has strong avalanche: a single-byte change cascades through the mixing steps and flips roughly half the output bits, producing a wildly different hash.

Does any of my data leave my browser?

Never. All hashing happens locally in JavaScript. Your input is not sent to, stored on, or logged by any server.