JSON Key Renamer

How to use

1. 1Paste your JSON document into the source field. Use Format input to pretty-print the source first if it helps you read the structure.
2. 2Add rules with Add literal, Add regex, or Add path. The sample loads several example rules so you can see each mode in action.
3. 3For literal rules, type the exact source key in From and the new key in To. Turn on Case-insensitive if you want Id, ID, and id to all match.
4. 4For regex rules, type a JavaScript pattern in From and a replacement template in To. Use $1 through $9 to reference capture groups and $& for the whole match.
5. 5For path rules, type a dot-notation path in From like users[*].id and the new key name in To. Use [n] for a specific array index, [*] for any element, and * for any object key.
6. 6Reorder rules with Up and Down. The first matching rule wins for each key, so place narrower rules above broader ones.
7. 7Pick an output style (2 spaces, 4 spaces, tab, or minified), then click Copy JSON to copy the renamed document.

About this tool

JSON Key Renamer rewrites JSON object keys using a list of rules you define, with a live preview of the renamed document, a per-rule hit count, and collision detection so renames never silently overwrite an existing key. Three rule modes are supported because real rename jobs land in three different shapes. Literal mode matches a key by exact name and renames every occurrence anywhere in the document (with an optional case-insensitive flag), which is the right tool for global normalization like rewriting Id to id everywhere or first_name to firstName everywhere. Regex mode matches keys against a JavaScript regular expression and rewrites them with a replacement template that supports $1 through $9 capture group references and $& for the whole match, which is the right tool for transforms like stripping a meta_ prefix from every key or rewriting anything ending in _at to a camelCase variant. Path mode targets a single key at a specific dot-notation location, including bracket indices for arrays and a * wildcard at any segment, which is the right tool for surgical renames like users[*].id -> userId on every element of an array without touching id fields elsewhere. Rules apply in their listed order; the first match for a key wins, so you can place broader rules below narrower ones. A live result panel renders the renamed JSON in your choice of 2-space, 4-space, tab, or minified output, with a copy button and stats tiles that show active rules, total renames, and collisions in real time. Collisions are surfaced per rule and the original key is kept rather than clobbering the conflicting existing key, so the output is always a structurally sound document. Parse errors from the source JSON are reported inline with the message the JavaScript engine produces, so you can see exactly where the input is malformed. Everything happens locally in your browser: the JSON you paste here, the rules you write, and the renamed output never leave your device, which makes the tool safe for normalizing API responses, refactoring config files, building data migration scripts, or aligning third-party payloads with your internal naming conventions.

Free to use. Works in your browser. No signup, no login.