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JSON Duplicate Keys Remover

Detect and remove duplicate keys in JSON objects. Choose to keep first or last occurrence. Reports all duplicates found. Runs in your browser.

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Reference
  
How does duplicate key detection work?
 
Standard JSON parsers silently keep only one value when an object has duplicate keys — usually the last one — and you lose visibility into the conflict. This tool uses a custom JSON tokenizer that records every key occurrence at every nesting level, reports each duplicate with its path, then rebuilds the JSON applying your chosen resolution strategy (keep first or last).
 
Common uses
 
  • API debugging — find why an endpoint silently drops fields.
  • Merged JSON — clean up after concatenating responses from multiple sources.
  • Schema validation — detect schema violations that JSON.parse hides.
  • Migration audits — verify no key collisions when merging configs.
 
Privacy
 
All processing runs 100% in your browser. No data is sent to any server.
  
    
    
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