Data Mapping Transformer

Rename, combine and reshape JSON records by rules.

Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.

Data Mapping Transformer

Rule shapes: {"from": "first", "to": "givenName"} renames; {"to": "fullName", "join": ["first", "last"], "sep": " "} joins; {"to": "city", "value": "Oslo"} sets a constant; {"from": "name", "to": "name", "upper": true} upper-cases.

How to use this tool

  1. Paste source records as a JSON array and mapping rules as a JSON array.
  2. Press Transform to see the reshaped records.
  3. Use Load sample: first and last become givenName and familyName.

Worked example

The sample record {"first": "Ana", "last": "Ray"} with rules renaming first to givenName and last to familyName gives {"givenName": "Ana", "familyName": "Ray"}. A join rule with join ["first", "last"] and sep " " on the same record gives fullName "Ana Ray".

What this tool does not do / Limits

Only flat, single-level records are reshaped: nested objects and arrays inside a record are copied as-is, not walked into. A rule naming a missing source field produces an empty string for that target, rather than failing the whole run.

Frequently asked questions

Can I drop a field?

Yes. Only fields named in rules appear in the output, so leaving a field out of the rules drops it.

What if the source is not a JSON array?

The tool reports that it needs a JSON array and does not guess at other shapes.

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