JSON Key Case Converter

Convert nested JSON keys between camelCase and snake_case—or choose PascalCase, kebab-case, or CONSTANT_CASE—without modifying values.

Local .json files · Pretty 2/4 or Minify · regex exclusions · stop paths · key diff · collision protection

Target key format

Output formatPreserve acronyms

JSON input

Drop a .json file here or choose one from your device

Files are read only in your browser. Maximum file size: 5 MB.

Converted JSON

{
  "userProfile": {
    "firstName": "Ada",
    "createdAt": "2026-09-12"
  }
}

Parsing, file reading, formatting, and key conversion run locally in your browser. JSON input is not sent to a conversion server.

Large JSON Engineering Mode

Process local JSON files up to 20 MB in a Web Worker, keep the page responsive, cancel work, and download the full converted result.

Key Diff is disabled in large-file mode to control memory usage.

Workflow presetTarget key formatOutput format

Advanced rules

Deep conversionConvert keys recursively inside nested objects and arrays. Turn off to change only the top object level.Preserve leading _ and $Keep semantic prefixes such as _id, __typename, and $schema while converting the rest of the key.Preserve acronymsKeep these keys unchangedKeep keys matching these regex patterns unchangedStop conversion below these paths

Drop a .json file up to 20 MB

The file is read locally and processed off the main UI thread.

The file stays on your device. Parsing and conversion run in a browser Web Worker.

What the JSON key converter changes

Only object keys are converted; string, number, boolean, null, and array values are preserved. Nested objects and objects inside arrays can be processed recursively, or Advanced object options can limit conversion to the top level. Exact or regex-matched source keys can be excluded, source-key stop paths can freeze selected subtrees, leading underscore and dollar prefixes can be preserved, and key collisions stop conversion instead of overwriting data.

Local JSON files

Drop or choose a .json file up to 5 MB. The browser reads it locally, and the output can be pretty-printed with 2 or 4 spaces or minified before download.

Stop paths

Convert a parent key but leave an exact nested subtree untouched, including arrays, using source-key dot paths such as data.raw_payload.

Exact and regex exclusions

Keep specific source keys unchanged or match groups of keys with JavaScript regular expressions such as ^__ or /_id$/i while still converting nested children.

Key-only diff

Inspect every renamed key with its source path, original name, and converted name without exposing scalar values in the diff.

JSON → camelCase

Use a focused page when your target is camelCase for JavaScript or TypeScript object properties.

JSON → snake_case

Use a focused page when your target is snake_case for Python, SQL, backend fields, or serialization conventions.

Related tools and guides

JSON → camelCase JSON → snake_case API Case Converter Object keys → camelCase in JavaScript Object keys → camelCase in TypeScript Object keys → snake_case in JavaScript