# fast-stringify > A blazing fast stringifier that safely handles circular objects Latest version **4.0.2** (published 2026-09-02) · MIT license · 0 weekly downloads ## Install ```sh npm install fast-stringify pnpm add fast-stringify yarn add fast-stringify bun add fast-stringify ``` ## Health **Score 70/100 (B)** — status: active. Positive: has types; esm support; no vulnerabilities; recently updated; high maintenance score; high quality score. Warnings: low downloads. ## Facts | | | |---|---| | Version | 4.0.2 | | Published | 2026-09-02 | | First published | 2018-06-03 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Dependencies | 0 | | Unpacked size | 73.9 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 53 | | Author | Tony Quetano | | Maintainers | planttheidea | | Keywords | stringify, fast, serialize, json | ## Links - npm: https://www.npmjs.com/package/fast-stringify - Repository: https://github.com/planttheidea/fast-stringify - Homepage: https://github.com/planttheidea/fast-stringify#readme - Issues: https://github.com/planttheidea/fast-stringify/issues - npm.io page: https://npm.io/package/fast-stringify ## Alternatives - [@mapbox/jsonlint-lines-primitives](https://npm.io/package/@mapbox/jsonlint-lines-primitives.md) — 5.3M weekly downloads - [reftools](https://npm.io/package/reftools.md) — 3.5M weekly downloads - [@hey-api/openapi-ts](https://npm.io/package/@hey-api/openapi-ts.md) — 3.5M weekly downloads - [@mapbox/geojson-rewind](https://npm.io/package/@mapbox/geojson-rewind.md) — 2.4M weekly downloads - [turbo-stream](https://npm.io/package/turbo-stream.md) — 1.7M weekly downloads ## Recent versions - 4.0.2 (latest) — 2026-09-02 - 4.0.0-beta.0 (next) — 2025-11-10 - 4.0.1 — 2026-07-08 - 4.0.0 — 2025-11-11 - 3.0.0 — 2025-09-26 - 3.0.0-beta.5 — 2025-09-26 - 3.0.0-beta.4 — 2025-09-26 - 3.0.0-beta.3 — 2025-09-26 - 3.0.0-beta.2 — 2025-09-26 - 3.0.0-beta.1 — 2025-09-26 - 3.0.0-beta.0 — 2025-09-25 - 2.0.0 — 2019-07-04 - 1.1.2 — 2019-07-04 - 1.1.1 — 2018-10-15 - 1.1.0 — 2018-08-09 - … 5 more at https://npm.io/package/fast-stringify/versions ## README # fast-stringify A tiny, [blazing fast](#benchmarks) stringifier that safely handles circular objects. The fastest way to stringify an object will always be the native `JSON.stringify`, but it does not support circular objects out of the box. If you need to stringify objects that have circular references, `fast-stringify` is there for you! It has a simple API to allow for several use-cases that `JSON.stringify` does not while also maintaining blazing fast performance compared to its peers. ## Table of contents - [fast-stringify](#fast-stringify) - [Table of contents](#table-of-contents) - [Usage](#usage) - [stringify](#stringify) - [Importing](#importing) - [Benchmarks](#benchmarks) - [Simple objects](#simple-objects) - [Complex objects](#complex-objects) - [Circular objects](#circular-objects) - [Special objects](#special-objects) - [Stable objects](#stable-objects) - [Stable circular objects](#stable-circular-objects) ## Usage ```javascript import { stringify } from 'fast-stringify'; const object = { foo: 'bar', deeply: { recursive: { object: {}, }, }, }; object.deeply.recursive.object = object.deeply.recursive; console.log(stringify(object)); // {"foo":"bar","deeply":{"recursive":{"object":"[ref=.deeply.recursive]"}}} ``` ### stringify ```ts interface Options { circularReplacer?: (key: string, value: any, referenceKey: string) => any; indent?: number | string; replacer?: (key: string, value: any) => any; stable?: boolean; stabilizer?: ( entryA: { key: string; value: any }, entryB: { key: string; value: any }, stabilizerOptions: { get: (key: string) => any }, ) => any; } function stringify(value: undefined | symbol | ((...args: any[]) => any), options?: Options): undefined; function stringify(value: Value, options?: Options): string; ``` Stringifies the object passed based on the options passed. The only required value is the `value`. The additional optons passed will customize how the string is compiled. Available options: - `replacer` => function to customize how the non-circular value is stringified (see [the documentation for JSON.stringify](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify) for more details) - `indent` => white space used to indent the stringified object for pretty-printing, either as a number of spaces or as the literal string to indent with (see [the documentation for JSON.stringify](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify) for more details) - `circularReplacer` => function to customize how the circular value is stringified (defaults to `[ref=##]` where `##` is the `referenceKey`) - `referenceKey` is a dot-separated key list reflecting the nested key the object was originally declared at - keys that would be ambiguous left bare, because they are empty or contain a `.`, `"`, or `\`, are quoted as JSON strings, so the path always identifies exactly one value: ```javascript stringify(nested); // {"x":{"y":{"z":{"back":"[ref=.x.y]"}}}} stringify(dotted); // {"x.y":{"z":{"back":"[ref=.\"x.y\"]"}}} ``` - `stable` => whether to sort the keys for stability - keys are sorted in ascending order by UTF-16 code unit, matching the default `Array.prototype.sort` ordering. Locale-aware comparison is deliberately not used, because it would make output vary between environments. - `stabilizer` => function to customize how the stable object is sorted (only applies when `stable` is `true`) `stringify` returns `undefined` rather than a string when `value` itself is not serializable, which is the case for `undefined`, functions, and symbols. Non-serializable values _nested_ within `value` always produce a string: keys on objects are omitted, and entries in arrays become `null`. ## Importing ```javascript // ESM import { stringify } from 'fast-stringify'; // CommonJS const { stringify } = require('fast-stringify'); ``` ## Benchmarks ### Simple objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ fast-stringify │ 1385041 │ '± 0.01%' │ │ faster-stable-stringify │ 1036269 │ '± 0.02%' │ │ fast-json-stable-stringify │ 1025641 │ '± 0.02%' │ │ json-stringify-safe │ 840336 │ '± 0.02%' │ │ json-stable-stringify │ 713266 │ '± 0.02%' │ │ decircularize │ 468823 │ '± 0.03%' │ │ superjson │ 272034 │ '± 0.03%' │ │ json-cycle │ 6976 │ '± 0.09%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "fast-stringify". ``` ### Complex objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ fast-stringify │ 227583 │ '± 0.05%' │ │ fast-json-stable-stringify │ 193535 │ '± 0.05%' │ │ faster-stable-stringify │ 176553 │ '± 0.06%' │ │ json-stringify-safe │ 142146 │ '± 0.07%' │ │ json-stable-stringify │ 112246 │ '± 0.08%' │ │ decircularize │ 61656 │ '± 0.10%' │ │ superjson │ 42057 │ '± 0.11%' │ │ json-cycle │ 1038 │ '± 0.62%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "fast-stringify". ``` ### Circular objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ fast-stringify │ 174703 │ '± 0.04%' │ │ fast-json-stable-stringify │ 151906 │ '± 0.07%' │ │ faster-stable-stringify │ 143843 │ '± 0.07%' │ │ json-stringify-safe │ 105218 │ '± 0.11%' │ │ json-stable-stringify │ 87382 │ '± 0.07%' │ │ decircularize │ 52408 │ '± 0.10%' │ │ superjson │ 30303 │ '± 0.13%' │ │ json-cycle │ 972 │ '± 0.20%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "fast-stringify". ``` ### Special objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ fast-stringify │ 81506 │ '± 0.05%' │ │ json-stringify-safe │ 54552 │ '± 0.09%' │ │ fast-json-stable-stringify │ 51421 │ '± 0.10%' │ │ faster-stable-stringify │ 47982 │ '± 0.10%' │ │ json-stable-stringify │ 34450 │ '± 0.11%' │ │ decircularize │ 20153 │ '± 0.13%' │ │ superjson │ 14992 │ '± 0.16%' │ │ json-cycle │ 384 │ '± 0.11%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "fast-stringify". ``` ### Stable objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ fast-json-stable-stringify │ 699300 │ '± 0.03%' │ │ faster-stable-stringify │ 679347 │ '± 0.04%' │ │ fast-stringify │ 580383 │ '± 0.03%' │ │ json-stable-stringify │ 415454 │ '± 0.04%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "fast-json-stable-stringify". ``` ### Stable circular objects ```bash ┌────────────────────────────┬─────────┬─────────────────┐ │ (index) │ Ops/sec │ Margin of error │ ├────────────────────────────┼─────────┼─────────────────┤ │ faster-stable-stringify │ 440722 │ '± 0.04%' │ │ fast-json-stable-stringify │ 430848 │ '± 0.04%' │ │ fast-stringify │ 358166 │ '± 0.04%' │ │ json-stable-stringify │ 275938 │ '± 0.05%' │ └────────────────────────────┴─────────┴─────────────────┘ Fastest was "faster-stable-stringify". ``` --- _Source: https://npm.io/package/fast-stringify · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._