Compare JSON side by side
online — free & instant
Paste two JSON objects and instantly see every difference highlighted. Added, removed, and changed values are color-coded for quick review. No signup, no server — runs entirely in your browser.
Open JSON Compare ToolFind every difference in three steps
No account. No upload. No nonsense.
Fully Private
Your JSON data never leaves your device. All comparison happens in JavaScript, right in your browser.
Deep Comparison
Recursively diffs nested objects and arrays at every level — nothing is missed regardless of depth.
Instant Results
No server round-trips. Comparison runs instantly, even for large JSON documents with thousands of keys.
Related JSON tools
Common questions answered
Is the JSON compare tool free?
Yes, completely free with no account or signup required. Compare as many JSON objects as you need.
What differences does the JSON diff tool detect?
The tool detects three types of differences: added keys (present only in the second JSON), removed keys (present only in the first JSON), and changed values (same key, different value). All differences are highlighted with color coding.
Does JSON compare work with nested objects and arrays?
Yes. The comparison is recursive — it traverses nested objects and arrays at every level, highlighting exactly where differences occur deep in the structure.
Is my JSON data sent to a server when comparing?
No. All comparison happens entirely in your browser using JavaScript. Your data never leaves your device — nothing is uploaded or stored.
Can I use this to review JSON changes in merge conflicts?
Yes. Paste the two conflicting JSON versions side by side and the diff tool will highlight every difference, making it easy to resolve merge conflicts visually.
What is JSON comparison?
JSON comparison evaluates whether two documents are structurally and semantically equivalent. Simple string equality fails when keys are in different orders or whitespace varies. Structural comparison normalizes both documents and compares their parsed representations — the correct way to determine if two payloads carry the same information.
This tool provides a side-by-side view where matching sections are aligned and differences highlighted. You can toggle between structural comparison (ignoring key order) and strict comparison (key order matters). For arrays, the tool supports both positional and value-based matching.
// Object A
{"name":"Alice","age":30}
// Object B
{"age":30,"name":"Alice"}
Structural: ✓ Identical (key order differs but values are the same) Strict: ✗ Different (key order matters in strict mode)
Get the most out of this tool
- Use structural comparison when checking if two APIs return equivalent data in different key orders.
- Use strict comparison when array order matters — for example, comparing sorted search results.
- Compare API responses before and after a refactor to verify the change does not alter the output.
Comparing JSON documents accurately
Comparing two JSON documents means finding the semantic differences between them — which keys were added, which were removed, and which values changed. Semantic comparison is fundamentally different from text comparison. Two JSON objects can produce identical parsed data while looking completely different as text (different indentation, different key order, different use of whitespace). A proper JSON comparison understands structure and ignores semantically irrelevant textual differences.
Key-order independence is the critical property that separates semantic JSON comparison from text diff. {"a":1,"b":2} and {"b":2,"a":1} are semantically identical JSON objects — both have the same keys and values. A text diff would show these as completely different. A semantic JSON diff reports zero differences. This matters enormously in practice: API responses and configuration files frequently serialize keys in different orders across versions or environments.
The comparison output format determines how useful the result is for debugging. Color-coded side-by-side view highlights added fields in green and removed fields in red — the classic diff UI familiar from code review tools. Inline annotation shows only the differing paths with their old and new values. RFC 6902 JSON Patch format produces a machine-readable list of operations that transforms the original into the target, useful for programmatic processing of differences.
Nested object comparison recurses into every level of nesting. If a top-level object has 10 keys and one of them contains a deeply nested object with 50 more keys, and only one of those 50 nested keys changed, the comparison correctly shows exactly that one change, not the entire parent object as changed. This precision is what makes JSON-aware comparison so much more useful than line-by-line text diffing for structured data.
Array comparison introduces ambiguity: should the comparison match array elements by position, by identity (a matching key like "id"), or by similarity? Position-based matching assumes arrays maintain stable positions — adding an element at the beginning causes every subsequent element to appear "changed". Identity-based matching (if elements have a unique ID field) correctly identifies insertions and deletions. This tool uses position-based matching by default but supports configuring a match key for object arrays.
JSON comparison is a first-class operation in many development workflows. Test frameworks compare expected vs actual JSON. Deployment pipelines compare proposed config changes vs current config. Database migration scripts compare schema versions. API gateway traffic mirrors compare primary vs canary response bodies. In all these contexts, precise JSON comparison — not text diff — is the right tool for understanding what actually changed.
When developers use this tool
Additional frequently asked questions
What is the difference between text diff and JSON semantic diff?
Text diff compares byte-for-byte. Two JSON documents with the same data but different key order, indentation, or whitespace show many text differences despite being semantically equal. JSON semantic diff normalizes the structure before comparing, reporting only meaningful data changes. Semantic diff is always the right choice for JSON data — text diff is only useful for exact source file comparison.
Does the comparison treat numbers and strings differently?
Yes. JSON has distinct number and string types. The value 42 (a number) and "42" (a string) are different in JSON, and the comparison reports them as different. This matches how JSON parsers treat them — most parsers would assign different types to these values in the target language, so the semantic difference is real and meaningful.
Can I compare JSON arrays where element order does not matter?
JSON arrays are ordered sequences, so by specification, [1,2,3] and [3,2,1] are different. However, for use cases where order is irrelevant (tag sets, permission lists), you can sort both arrays before comparing. The comparison tool sorts arrays if you enable the "order-independent array comparison" option, treating them as sets for comparison purposes.
How is JSON comparison different from JSON diff?
JSON comparison and JSON diff refer to the same operation — finding differences between two JSON documents. The term "compare" emphasizes the visual side-by-side presentation; "diff" emphasizes the programmatic list of changes (especially RFC 6902 JSON Patch format). This tool provides both the visual comparison and the exportable diff format.