JSON unique by field

Client

Deduplicate a JSON array of objects using one property—choose whether to keep the first or last row for each distinct field value.

Learn more: deduplicating by one field

Walk a root array and keep one object per distinct value of a chosen property—first or last row wins.

Not full-row equality

Two rows with the same field value but different other columns still count as duplicates. Only the named property matters.

Nearby workflows on Toolcore

  • JSON group by field — Bucket a root array of objects by one property—object of arrays output; local only. once JSON text parses on this page.
  • Sort JSON array by field — Sort a JSON array of objects by one property—asc or desc; local only. once JSON text parses on this page.
  • JSON cleaner — Remove null and optional empty values recursively—pretty-printed output; local only. once JSON text parses on this page.
  • JSON formatter — JSON format online: pretty-print, minify, validate, escape, download . once JSON text parses on this page.

Unique rows by field

?

Deduplicate an array of objects using one property. Nested objects and arrays inside rows are not compared—only the top-level field value.

Which duplicate to keep

Removed 1 duplicate row.

Common use cases

  • Collapse duplicate user or SKU rows after merging exports from two systems.
  • Keep one record per email or ID before importing into a database or spreadsheet.
  • Trim repeated log events that share the same correlation field.

Common mistakes to avoid

  • Expecting deep equality

    Only the chosen top-level field value decides uniqueness. Other columns can differ.

  • Comparing composite keys

    For multi-column uniqueness, run pick-keys first or normalize into one synthetic field.

FAQ

First vs last row?

Keep first preserves the earliest row for each field value; keep last keeps the final one.

Does this work on nested arrays?

The root must be an array of objects. Nested arrays inside each object are left unchanged.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • json dedupe by field
  • unique json array by property
  • remove duplicate json objects

More tools

Related utilities you can open in another tab—mostly client-side.