ArrayDiff is a free developer tool for comparing arrays and JSON data side by side. It highlights what was added, removed, or changed — with color-coded visual diffs. It works with data from any language (Python, JavaScript, PHP, Ruby, Go, Java) and runs entirely in your browser for complete privacy.
Common Use Cases:
API TestingConfig ValidationData MigrationTest AssertionsCode ReviewGet started in three simple steps. For the full walkthrough with keyboard shortcuts and format tips, read the complete guide.
Copy and paste your arrays (from any programming language) into the two input panels. Supports arrays with strings, numbers, objects, and nested arrays from Python, JavaScript, PHP, Ruby, Go, and more.
Click "Compare Arrays" to see the differences highlighted in real-time. Added elements are green, removed are red, and modified are yellow.
Review the detailed comparison results with element counts and visual indicators for each type of change.
Practical examples where array comparison saves developers time and prevents bugs. See the full examples page with live diffs for each scenario.
Compare REST API responses before and after version updates to ensure backward compatibility.
Before: [{"id": 1, "name": "John"}] → After: [{"id": 1, "name": "John", "email": "john@example.com"}]Validate configuration arrays across different environments to prevent deployment issues.
Staging: [{"feature": "auth", "enabled": true}] vs Prod: [{"feature": "auth", "enabled": false}]Compare expected vs actual test results to identify failures and data inconsistencies.
Expected: [{"status": "success", "count": 5}] vs Actual: [{"status": "success", "count": 3}]Compare database query results before and after migration to ensure data integrity.
Old: [{"user_id": 1, "role": "admin"}] → New: [{"userId": 1, "permissions": ["read", "write"]}]Everything runs in your browser. Your data never leaves your device — no server uploads, no tracking of input content.
Color-coded results: green for added, red for removed, yellow for modified. Spot changes at a glance.
Recursively compares nested objects, arrays within arrays, and complex JSON structures at any depth.
Keyboard shortcuts (Ctrl+Enter to compare, Ctrl+L for sample data), syntax highlighting, and mobile support.
Pure JavaScript with no external libraries. Loads instantly, works offline once loaded, and handles large datasets efficiently.
Accepts JSON arrays, Python lists, JavaScript arrays, and any structured data that can be represented as JSON.
Free browser-based tools for everyday dev tasks. All private, all instant.
Diff & Compare
Compare two JSON objects or documents. See added, removed, and changed keys with path-based highlighting.
Compare plain text or code line by line with word-level highlighting. Side-by-side view.
Compare CSV or TSV files with a table-based view. Custom delimiters and key column matching.
Encode / Decode / Format
Format, beautify, minify, and validate JSON with customizable indentation and key sorting.
Encode text to Base64 or decode Base64 back to text. Full UTF-8 support.
Encode URLs with encodeURI or encodeURIComponent. Decode percent-encoded strings.
Decode JSON Web Tokens to view header, payload, and signature with expiry status.
Generate & Convert
Build and test regular expressions with real-time highlighting, match groups, and flag support.
Generate random v4 UUIDs in bulk. Validate existing UUIDs and copy with one click.
Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes from any text input.
Convert between Unix timestamps and human-readable dates in multiple formats and timezones.
Convert between YAML and JSON formats instantly. Preserve nested structures and data types.
ArrayDiff works with data from any programming language. Paste your arrays in JSON format and compare them instantly — no plugins, no installs, no server-side processing.
Compare Python lists and dictionaries. Convert your Python data to JSON format (json.dumps()) and paste it directly. Perfect for debugging data pipelines, comparing pandas DataFrames exported as JSON, and validating ETL outputs.
Diff JavaScript arrays and objects side by side. Works with JSON.stringify() output from React state, Redux stores, API responses, and Node.js data structures. Debug state changes visually.
Deep compare JSON objects at any nesting level. See exactly which keys were added, removed, or modified. Ideal for API response testing, configuration file comparison, and schema migration validation.
Compare PHP arrays by converting them with json_encode(). Debug associative arrays, validate Laravel/Symfony config differences, and compare database query results across environments.
Compare Go slices and maps by marshaling to JSON with json.Marshal(). Useful for comparing API responses, testing data transformations, and validating microservice outputs.
Got questions? See the full FAQ page for detailed answers.
ArrayDiff compares the parsed data structure, not raw text. This means insignificant whitespace, trailing commas, and formatting differences are ignored. Only actual value changes are shown. For raw text comparison, use the Text Diff tool.
Yes. Since ArrayDiff works with JSON, you can compare a Python list against a JavaScript array or any other language's output. Just serialize both to JSON and paste them in.
Once the page loads, all comparison logic runs locally in your browser with zero server calls. You can disconnect and continue comparing. This also means your data stays entirely on your device — see our privacy policy.
Green = added (in Array 2 only), Red = removed (in Array 1 only), Yellow = modified (same position, different value), Gray = unchanged. The summary bar at the top shows counts for each type.