What is JSON Diff?
Diff two JSON documents and surface structural changes. Highlights added, removed, and modified keys with a side-by-side view.
Before you use this tool
Use a small copy first, then inspect delimiters, encoding, numbers, dates, and missing values. A file can be valid and still be wrong for the system that will read it next. The safest tool is the one whose limits you understand.
Deep Dive: JSON Diff
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Core Capabilities
- Compare two JSON documents
- List added, removed, and changed keys
- Show before and after values
- Handles nested objects and arrays
- No upload of either document
- Runs offline after the page loads
Why It Matters
- Privacy: both documents stay in your browser during comparison.
- Precision: reports changed values, not just line differences.
- Clarity: added, removed, and changed are colour-coded.
- Speed: the comparison runs the moment both sides are valid.
Quick Start Guide
Paste the original JSON into the left box.
Paste the changed JSON into the right box.
Read the list of added, removed, and changed keys with their values.
Fix the flagged paths or copy the result for your changelog.
Usage Examples
Changed value
Scenario 01Same key, different value
{"status": "active", "count": 1}changed: count 1 → 2
Common Scenarios
Reviewing config changes
Spot what moved between two versions of a settings file.
Auditing API responses
Compare a response before and after a backend change.
Questions?
Technical Architecture
How the comparison works
Both documents are parsed with the browser's JSON parser, then flattened into key paths (for example user.address.city or items[0].sku). The two path maps are compared so the result reflects structure and values, not line order or formatting.
Why not a plain text diff
Reordering keys or reindenting a file produces many text-diff lines even when nothing changed. A key-level diff ignores presentation and reports only the fields whose value actually differs, which is what matters when reviewing a config or payload.
From diffing to other JSON tasks
Once you know what changed you can reformat either document with the JSON Formatter, confirm validity with the JSON Validator, or reshape it with JSON to CSV or JSON to YAML. All run locally.
Keep Exploring
Power up your workflow with related utilities.
Related Tools
JSON Formatter
The definitive JSON workshop for developers. Transform minified payloads into readable structures, catch syntax errors in real-time, and prepare your data for production with zero cloud exposure.
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Validate your JSON syntax and structures. Highlight missing brackets or trailing commas with line-specific errors right in your browser thread.
Use free →JSON Viewer
Render JSON as an interactive, collapsible tree. Expand and collapse nodes, search keys, and inspect structure without uploading data.
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Founder & Lead Developer at FileMint
Building privacy-first browser tools powered by WebAssembly. Focused on making file processing fast, secure, and accessible — without ever uploading your data to a server.
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