# fast-fnv1a > An extremely fast 32-bit FNV-1a hash implementation for JavaScript, up to 6x faster than alternatives. Latest version **1.0.0** (published 2026-07-26) · MIT license · 0 weekly downloads ## Install ```sh npm install fast-fnv1a pnpm add fast-fnv1a yarn add fast-fnv1a bun add fast-fnv1a ``` ## Health **Score 75/100 (B)** — status: active. Positive: has types; esm support; no vulnerabilities; has provenance; recently updated; high maintenance score; high quality score. Warnings: low downloads. ## Facts | | | |---|---| | Version | 1.0.0 | | Published | 2026-07-26 | | First published | 2026-07-26 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | ^22.15.0 \|\| ^23.8.0 \|\| >=24.0.0 | | Dependencies | 0 | | Unpacked size | 9 KB | | Known vulnerabilities | 0 | | Install scripts | no | | Provenance | attested (GitHub Actions) | | GitHub stars | 1 | | Author | SukkaW | | Maintainers | sukkaw | | Keywords | fnv, fnv1a, fnv-1a, hash, fast | ## Links - npm: https://www.npmjs.com/package/fast-fnv1a - Repository: https://github.com/SukkaW/fast-fnv1a - npm.io page: https://npm.io/package/fast-fnv1a ## Alternatives - [babylon](https://npm.io/package/babylon.md) — 5.1M weekly downloads - [csscolorparser](https://npm.io/package/csscolorparser.md) — 3.7M weekly downloads - [expr-eval-fork](https://npm.io/package/expr-eval-fork.md) — 1.5M weekly downloads - [@leeoniya/ufuzzy](https://npm.io/package/@leeoniya/ufuzzy.md) — 247.7K weekly downloads - [xml-parser](https://npm.io/package/xml-parser.md) — 78.4K weekly downloads ## Recent versions - 1.0.0 (latest) — 2026-07-26 - 1.0.0-beta.1 (next) — 2026-07-26 - 0.0.0 — 2026-07-26 ## README # fast-fnv1a A fast 32-bit [FNV-1a](https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function) hash implementation for JavaScript, **up to 6x faster than alternatives**. [The same implementation is adopted by `fastify-etag` and see 2x performance boost with large responses](https://github.com/fastify/fastify-etag/pull/152). The implementation is based on prior work by [@tjwebb](https://github.com/tjwebb) (Travis Webb) and [@desudesutalk](https://github.com/desudesutalk) under the MIT license, with extra simplifacations and optimizations (like inline lookup table and faster hex conversion). The classic 32-bit FNV-1a is usually written with a chain of shifts and adds to emulate the 32-bit multiply. That forces the value out of the small-integer range on every character, so the engine keeps boxing it as a double. This implementation instead carries the hash as two 16-bit halves, which stay inside the small-integer range throughout — making it **up to 6x faster**. > If you need a larger hash space, check out [fnv1a52](https://github.com/SukkaW/fnv1a52) for 52 bits (still a plain `number`, w/o `BigInt`), or [@danielroe](https://github.com/danielroe)'s [fnv1a-64](https://github.com/danielroe/fnv1a-64) for full 64 bits hash space. ## Install ```sh pnpm add fast-fnv1a yarn add fast-fnv1a npm install fast-fnv1a ``` ## Usage ```js import { fnv1a, fnv1ahex } from 'fast-fnv1a'; console.log(fnv1a('hello world')); //=> 3582672807 console.log(fnv1ahex('hello world')); //=> 'd58b3fa7' ``` > You should NEVER `fnv1a().toString(16)`! `fnv1ahex` can get you a fixed length zero-padded hex string **up to 3.9x faster** via a byte-to-hex lookup table. ## API ### `fnv1a(str)` Returns the 32-bit FNV-1a hash of `str` as an unsigned `number`. - **str**: `string` ### `fnv1ahex(str)` Returns the 32-bit FNV-1a hash of `str` as a lowercase hexadecimal `string` (fixed length, zero-padded to 8 characters). - **str**: `string` Prefer this over `fnv1a(str).toString(16)` — it uses a byte-to-hex lookup table and is up to 3.9x faster. Note the fixed length means this is **not** always equal to `fnv1a(str).toString(16)`: a hash below `16 ** 7` keeps its leading zero here, while `toString(16)` drops it. ## Benchmark Hashing `'the quick brown fox jumps over the lazy dog'`, compared against [`fnv1a`](https://www.npmjs.com/package/fnv1a) and [`@sindresorhus/fnv1a`](https://www.npmjs.com/package/@sindresorhus/fnv1a): ``` $ pnpm run bench clk: ~3.27 GHz cpu: Apple M2 Max runtime: node 24.18.0 (arm64-darwin) • fnv1a ------------------------------------------------- ------------------------------- fnv1a 298.12 ns/iter @sindresorhus/fnv1a 1.14 µs/iter fast-fnv1a 69.17 ns/iter • hex ------------------------------------------------- ------------------------------- fnv1a + toString(16) 627.36 ns/iter @sindresorhus/fnv1a + toString(16) 1.10 µs/iter fast-fnv1a + toString(16) 356.68 ns/iter fnv1ahex 92.01 ns/iter ``` Note that `@sindresorhus/fnv1a` hashes UTF-8 bytes and returns a `BigInt`, so it is not a drop-in equivalent — it produces different values for non-BMP input and costs an allocation per call. `fnv1a` and `fast-fnv1a` both hash UTF-16 code units and agree on all inputs. ## License [MIT](LICENSE) ---- **fast-fnv1a** © [Sukka](https://github.com/SukkaW), Released under the [MIT](./LICENSE) License. Authored and maintained by Sukka with help from contributors ([list](https://github.com/SukkaW/fast-fnv1a/graphs/contributors)). > [Personal Website](https://skk.moe) · [Blog](https://blog.skk.moe) · GitHub [@SukkaW](https://github.com/SukkaW) · Telegram Channel [@SukkaChannel](https://t.me/SukkaChannel) · Mastodon [@sukka@acg.mn](https://acg.mn/@sukka) · Twitter [@isukkaw](https://twitter.com/isukkaw) · BlueSky [@skk.moe](https://bsky.app/profile/skk.moe)

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