97% Smaller, 2x Faster: How es-toolkit Surpassed 10 Million Weekly Downloads

es-toolkit is a JavaScript utility library built from scratch by Toss's frontend team to replace lodash. Designed around ES Modules and TypeScript from the ground up, it focuses on boosting tree shaking, type safety, and runtime performance together in modern browser and engine environments.

The core difference is clear. For the same functionality, bundle size is up to 97% smaller, and runtime is 2-3x faster. Using es-toolkit/compat lets you replace lodash almost as-is, so it can be applied directly to existing projects without code changes.

The difference in performance and size comes from the structure. lodash-es is the ES Modules version, but internal helper dependencies remain, so importing a single function still pulls in extra code. In contrast, each function in es-toolkit is fully independent, so you only bring in what you need, and since it doesn't rely on a separate type package like @types/lodash, types are managed together with the source.

Benchmark examples were also presented. sample shrinks from about 2,000 bytes in lodash to about 88 bytes in es-toolkit, roughly a 96% reduction, and omit is explained to be 11.8x faster at runtime. However, the 97% figure is not an average across all functions, but closer to the maximum reduction observed.

Adoption has been fast. Within 18 months of launch, npm weekly downloads surpassed 10 million, and teams such as Microsoft, Yarn, Storybook, IBM, Recharts, and Ink adopted it after internal validation. Without any deliberate viral push, smaller bundles, faster execution, and a better typing experience drove real adoption.

Migration is also simple. The easiest method is adding "lodash": "npm:es-toolkit@^1.44.0" to package.json, and more directly, you can change lodash-es imports to es-toolkit imports. A codemod (@es-toolkit/codemod), an official guide, and performance documentation are provided for this, and Node.js, Deno, Bun, browser, and CDN deployment are all supported.

Toss is continuing broader open source activity with es-toolkit as a starting point. It has an Open Source Committee within its Frontend Chapter, and is also developing libraries such as overlay-kit, use-funnel, and suspensive. The message is simple: even an old utility stack can see major improvements in both size and speed when rebuilt to match modern assumptions.