camelCase変換

camelCase converter: turn phrases into JavaScript-style identifiers

camelCase joins words without spaces: the first word stays lowercase and each following word starts with a capital letter. You see it everywhere in JavaScript object keys, JSON API fields, React prop names, and TypeScript variables. This tool splits messy input—Title Case labels, snake_case columns, or plain English phrases—and outputs a single camelCase token you can paste into code.

Paste a human-readable label like “user profile id” or “max retry count” and get userProfileId or maxRetryCount instantly. Copy the result into your editor, OpenAPI spec, or database migration. For class names and React components, use our PascalCase converter instead; for Python and SQL, try snake_case.

What camelCase is (and how it differs from PascalCase)

camelCase and PascalCase both glue words together, but PascalCase capitalizes the first word too: UserProfileId versus userProfileId. JavaScript convention uses camelCase for variables and functions, PascalCase for classes and components. Mixing them in one codebase creates lint noise and confuses new contributors.

This converter follows the common programming rule: lowercase the first segment, then capitalize the first letter of each subsequent word. Numbers and acronyms can be tricky—paste “API key” and review whether you want apiKey or aPIKey for your style guide.

How the tool splits words from messy input

The converter recognizes spaces, hyphens, underscores, and transitions between lowercase and uppercase letters. That means user_profile_id, user-profile-id, and UserProfileId all normalize to the same word list before camelCase is applied.

Punctuation and accents are stripped or simplified so identifiers stay ASCII-safe for most codebases. If you need to preserve a specific spelling, edit the output manually—automatic splitting cannot know every brand name or acronym rule your team enforces.

JavaScript, TypeScript, and JSON APIs

Modern front-end codebases expect camelCase for variables, function names, and object properties. When you import CSV headers or spreadsheet columns named “First Name” and “Order ID,” converting them before mapping to JSON saves repetitive rename work.

REST and GraphQL schemas often document camelCase field names even when the database uses snake_case. Run column names through this tool, then through snake_case if you need both views. Keeping a naming cheat sheet next to your repo prevents drift between layers.

camelCase vs snake_case: when to use which

Python, Ruby, and many SQL style guides prefer snake_case (user_profile_id). JavaScript and Java ecosystems lean camelCase. JSON payloads crossing language boundaries are a frequent source of bugs when one service sends user_id and another expects userId.

If you are standardizing a greenfield API, pick one convention and document it. Use this converter to batch-rename legacy keys exported from analytics or CMS fields before you publish a new schema version.

Workflow tips with other Case Modify tools

A practical pipeline: lowercase noisy ALL CAPS labels, camelCase them for code, or snake_case them for migrations. Kebab-case fits URL slugs; dot.case fits translation keys. Chaining converters beats manual retyping when you inherit a messy export.

For documentation examples, convert once and save the output in your snippet library. Readers learn faster when variable names match the casing they will see in production repos.

Before and after examples

Acronyms and product names may need a manual pass after conversion.

Frequently asked questions

Guides and deeper reading

• What is camelCase?
• camelCase vs snake_case
• Sentence case vs title case