JSON union all rows
ClientStack two JSON row arrays in order (union all)—keep duplicates when you need one combined list before dedupe.
Learn more: JSON union all
Concatenate two JSON row arrays in order (union all)—keep duplicates—when you need one combined list without deduplication by key.
Union all vs distinct
Union all preserves every row from both sides, including duplicates. Use dedupe-by-key tools afterward if you need unique keys only.
Ordering
Rows from the first array appear before rows from the second. Stable order matters for diffing and replay tests—note which snapshot was left vs right.
Privacy
Concatenation is local; no server-side merge.
About JSON union all rows
Stack two JSON row arrays (union all)—local. Parsing and transforms run in your browser—Toolcore does not upload your JSON for this operation.
How to use
Paste a JSON array (or follow the two-array example on join tools). Use Load example when shown, or prefill with ?q= / ?qb= on the tool URL.
Input and limits
Fix JSON syntax errors before expecting output. Very large arrays may slow the tab—trim samples during exploration, then scale up locally.
Nearby workflows on Toolcore
- JSON formatter — JSON format online: pretty-print, minify, validate, escape, download . Useful once JSON parses on this page.
- JSON replace values — Replace every value equal to from with to—use from|to, JSON or plain text. Useful once JSON parses on this page.
- JSON filter field by regex — Keep rows whose string field matches a regular expression—local. Useful once JSON parses on this page.
- JSON count field nulls — Count null or missing values for one row field—metadata. Useful once JSON parses on this page.
Common use cases
- Stack two JSON row batches in order without removing duplicates.
- Append nightly export B to export A for a combined local analysis pass.
- Prepare union-all fixtures before dedupe-by-key tools.
Common mistakes to avoid
Expecting automatic deduplication
Union all keeps duplicates—dedupe tools remove repeated keys afterward.
Mismatched row shapes
Rows with different keys still concatenate; sparse columns are normal in the combined array.
Reversed order expectations
First array rows appear before second array rows—swap inputs if order matters.
FAQ
Is data uploaded?
No—concatenation is local.
Union all vs SQL UNION?
This page keeps all rows including duplicates, like SQL UNION ALL.
Agent prefill?
Use ?q= or ?qb= for the JSON payload.
More tools
Related utilities you can open in another tab—mostly client-side.
JSON formatter
ClientJSON format online: pretty-print, minify, validate, escape, download .json.
JSON replace values
ClientReplace every value equal to from with to—use from|to, JSON or plain text.
JSON filter field by regex
ClientKeep rows whose string field matches a regular expression—local.
JSON count field nulls
ClientCount null or missing values for one row field—metadata.