JSON anti-join on key
ClientReturn left-side rows whose key is missing from the right array—SQL-style anti-join for orphan detection.
Learn more: JSON anti-join
Return rows from the left array whose key value does not appear in the right array—SQL-style anti-join for finding missing records between two JSON snapshots.
Two arrays, one key
Paste JSON with two row arrays (see the page example). Specify the key field name—often id or email. Output lists left-side rows with no match on the right.
Typical uses
Find users in export A who never appear in export B, or SKUs staged but not yet in catalog JSON. Follow with union or symmetric difference tools for fuller set logic.
Privacy
Comparison runs locally; paste redacted samples when keys identify people.
About JSON anti-join on key
Rows in A missing from B on a shared key—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
- Find records present in export A but missing from export B on a shared id key.
- Reconcile staging vs production JSON snapshots without SQL.
- Identify orphaned rows before a migration cutover.
Common mistakes to avoid
Wrong key field name
The key must exist on rows in both arrays—typo in the field name yields false misses.
Type mismatch on keys
String "1" and number 1 do not match—normalize types with replace-values tools first.
Expecting symmetric difference
Anti-join is left-only; use symmetric difference for rows exclusive to either side.
FAQ
How many arrays do I paste?
Follow the page example—typically two row arrays compared on one key field.
Is comparison done on Toolcore servers?
No—all set logic runs locally.
Can I prefill JSON only?
Yes—?q= / ?qb= for JSON; edit the key parameter on the page.
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.