97% Smaller, 2x Faster: How es-toolkit Reached 10 Million Weekly Downloads (opens in new tab)

es-toolkit is a modern, TypeScript-first JavaScript utility library designed as a faster and smaller alternative to lodash. Built around ES Modules and independent functions, it can reduce bundle sizes by up to 97% and improve runtime performance by more than 2x. Its es-toolkit/compat package provides a 100% lodash-compatible migration path with little or no code changes.

Why es-toolkit was created

• Toss’s frontend team saw an opportunity to modernize the utility-library ecosystem.
• lodash was designed before ES Modules, advanced JavaScript engines, TypeScript, and bundle size became central concerns.
• es-toolkit was built from scratch with:
  • Native ES Module support
  • Tree-shaking-friendly independent functions
  • Built-in TypeScript definitions
  • Modern runtime optimizations

Bundle size and runtime performance

• lodash-es can include internal helper dependencies even when importing a single function.
• es-toolkit functions are designed to be independent, avoiding hidden dependencies.
• A sample set of five functions—groupBy, keyBy, pick, omit, and debounce—adds roughly:
  • 30 KB with lodash-es
  • 1 KB with es-toolkit
• The library reports up to 97% smaller bundles and more than 2x faster execution.
• Specific benchmarks include:
  • sample: approximately 2,000 bytes in lodash versus 88 bytes in es-toolkit
  • omit: approximately 11.8x faster at runtime

Adoption and ecosystem support

• es-toolkit surpassed 10 million weekly npm downloads within 18 months.
• It has been adopted by Microsoft, Yarn, Storybook, IBM, Recharts, Ink, and Dify.
• The article emphasizes that adoption came through independent evaluations and benchmarks rather than major promotional campaigns.

Migration from lodash

• Most imports can be changed directly:

  import { pick } from 'es-toolkit';
  

• es-toolkit/compat provides a drop-in lodash replacement with full compatibility, validated against lodash’s test suite.

• Existing projects can redirect the lodash dependency without changing source code:

  {
    "dependencies": {
      "lodash": "npm:es-toolkit@^1.44.0"
    }
  }
  

• Teams can later migrate from compatibility imports to native es-toolkit imports for additional bundle and performance benefits.

• An official @es-toolkit/codemod tool is available to automate migration.

TypeScript and maintenance

• Type definitions are shipped alongside the implementation and are kept synchronized.
• This avoids the version mismatches and inaccuracies possible with lodash’s separately maintained @types/lodash package.
• The project is actively maintained, with regular additions and responsive issue and pull-request handling.

Project direction

• es-toolkit is part of Toss’s broader open-source initiative.
• Related projects include:
  • overlay-kit for Promise-based React overlays
  • use-funnel for type-safe multi-step flows
  • suspensive for React Suspense primitives
• The library is MIT licensed and installable with npm install es-toolkit.

For most lodash users, the recommended approach is to start with the compatibility alias for an immediate, low-risk upgrade, then progressively adopt native es-toolkit imports to maximize bundle-size and performance improvements.