JSON Structure Compare

Paste two JSON documents to compare their structure — keys and value types — while ignoring the actual values. Ideal for checking whether two API responses share the same shape.

What structure comparison tells you

Two JSON documents can hold completely different data yet still follow the same contract. This tool checks exactly that: it walks both documents together and reports every key that exists on only one side and every field whose type differs — a string id in one response against a numeric id in the other, for example. The values themselves never influence the result.

That makes it the right check when a value-level diff would drown you in noise: comparing responses from two API versions, validating that staging matches production, or checking a mock against the real endpoint.

Worked example

JSON A:

{ "id": 1, "user": { "name": "Asha", "email": "[email protected]" } }

JSON B:

{ "id": "1", "user": { "name": "Ravi", "phone": "555-0100" } }

Report — the name difference is correctly ignored, everything structural is caught:

✖ Structures differ — 3 difference(s) found.

Only in JSON A (1):
  $.user.email

Only in JSON B (1):
  $.user.phone

Type mismatches (1):
  $.id — number in JSON A, string in JSON B

When to use it

• Confirming that a new API version kept its response shape backward-compatible.
• Checking that a hand-written mock or fixture still matches the real endpoint.
• Comparing configuration files across environments where values are supposed to differ but fields are not.
• Reviewing whether two records in a collection follow the same schema before writing import code.

Limitations to know

• In the default array mode only the first element of each array is inspected; a malformed element deeper in a list only surfaces in “every index” mode.
• The report tells you shapes differ, not which side is “correct” — that judgement needs your API contract or schema. For contract-first validation, generate a schema with the JSON to JSON Schema converter instead.
• Both inputs must be valid JSON; a syntax error is reported with its line and column before any comparison runs.

Common errors and fixes

• “JSON A is not valid JSON (line X, column Y)” — the input has a syntax problem such as a trailing comma or single quotes; the message names the exact spot to fix.
• Everything reports as “only in A” — usually one document is wrapped in an extra container (like {"data": {...}}) and the other is not; unwrap one side so the roots align.
• Array differences not detected — switch the array option to “compare every index”; the default schema-style mode intentionally checks only the first element.

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