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Fix JSON duplicate keys

JSON allows duplicate keys, but most parsers use only the last value. Duplicate keys can cause bugs and unexpected behavior.

Common causes

  • Same key repeated in an object.
  • Copy-paste or merge errors.
  • Generated JSON from multiple sources.

How to fix

  • Remove duplicate keys and keep a single value per key.
  • Use a JSON validator to detect duplicates.
  • Consider a schema to enforce uniqueness.

Use our tool

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