change-case

change-case is a small, dependency-free TypeScript library for converting strings between virtually every common casing convention — camelCase, PascalCase, snake_case, kebab-case (param-case), CONSTANT_CASE, Capital Case, dot.case, path/case, and more — as one package exporting a dedicated function per case.

As of v5, the project consolidated what used to be a dozen+ separately published packages (camel-case, pascal-case, snake-case, param-case, etc.) into this single change-case package sharing one word-splitting engine, so consumers pull in one dependency instead of a chain of tiny ones.

What You Get

• Dedicated conversion functions for camelCase, pascalCase, snakeCase, kebabCase, constantCase, capitalCase, dotCase, pathCase, sentenceCase, and more, all from one package
• A shared, locale-aware split() word-boundary engine that correctly handles Unicode, acronyms, and embedded numbers
• Configurable options per conversion (custom delimiter, prefix/suffix character preservation, custom split function)
• Zero runtime dependencies and full TypeScript types out of the box
• Companion packages (sponge-case, swap-case, title-case) in the same monorepo for less common transformations

Common Use Cases

• Converting API response keys from snake_case to camelCase (or vice versa) at a serialization boundary
• Generating consistent file, class, or variable names from user input or CMS-entered titles in a code generator
• Normalizing CSS class names or HTML attribute names between kebab-case and camelCase in a styling utility
• Building CLI scaffolding tools that need to derive multiple casing variants of a single project/feature name

Under The Hood

Architecture — The monorepo (managed via ts-scripts) currently ships four packages under packages/: the consolidated change-case package containing every mainstream case converter as named exports from one src/index.ts, plus three standalone packages (sponge-case, swap-case, title-case) for transformations that don’t fit the shared splitting model. change-case’s core is a regex-based split() function using Unicode-aware patterns (\p{Ll}, \p{Lu}) to find word boundaries across lower-to-upper transitions, consecutive-uppercase acronym boundaries, and embedded digits, then every case function (camelCase, snakeCase, etc.) is a thin wrapper that calls split() and re-joins words with the right delimiter and capitalization rule. Tech Stack — Pure TypeScript, ESM-only (type: module), built and tested via the shared ts-scripts tooling with Vitest for both specs (*.spec.ts) and benchmarks (bench script), no runtime dependencies at all. Code Quality — Every exported function has a colocated .spec.ts file (index.spec.ts, keys.spec.ts) exercising edge cases like consecutive acronyms and Unicode input; the package is feature-complete and stable but has seen no commits in roughly a year, reflecting a mature, effectively ‘done’ library rather than active development. API Design — The v5 redesign’s biggest ergonomic win is exporting every case function from one root import (import { camelCase, snakeCase } from 'change-case') instead of installing a separate package per case, while keeping each function’s signature simple (string in, options object optional, string out) with no class instances or configuration objects required for the common path.