JSON merge arrays by key
ClientLightweight left-join style merge for two JSON tables without SQL or jq.
Learn more: merge by key
Right rows without a left match are omitted—unmatched left rows stay unchanged.
Local processing
Parsing and output formatting run entirely in your browser—nothing is uploaded for this transform.
Input
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Nearby workflows on Toolcore
- JSON deep merge — Merge two objects recursively—right overlays left; dual JSON prefill. once JSON text parses on this page.
- 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.
- JSON unique by field — Deduplicate JSON array rows by one field—keep first or last; local only. once JSON text parses on this page.
- CSV ↔ JSON — Paste a table or JSON array of objects—convert both ways, choose delimiter, client-side. once JSON text parses on this page.
Common use cases
- Lightweight left-join style merge for two JSON tables without SQL or jq.
Common mistakes to avoid
Invalid JSON
Fix parse errors before expecting output.
FAQ
Is data uploaded?
No—all parsing and transforms run locally.
How is this different from jq?
This page focuses on one deterministic task without a filter language.
More tools
Related utilities you can open in another tab—mostly client-side.
JSON deep merge
ClientMerge two objects recursively—right overlays left; dual JSON prefill.
JSON group by field
ClientBucket a root array of objects by one property—object of arrays output; local only.
JSON unique by field
ClientDeduplicate JSON array rows by one field—keep first or last; local only.
CSV ↔ JSON
ClientPaste a table or JSON array of objects—convert both ways, choose delimiter, client-side.