JSON Transform Tool — Powerful JSON Data Transformation
What is JSON Transform?
The JSON Transform Tool lets you shape and transform JSON data using simple, intuitive rules. Pick specific fields, filter arrays, rename keys, and map values-all 100% in your browser with no data leaving your device.
Perfect for:
- API response shaping
- Data cleaning and preparation
- Flattening nested structures
- Removing sensitive fields
- Renaming keys for consistency
Core Features
1. Pick Fields
Select only the fields you need. Removes all other data.
Pick: user.name, user.email
2. Remove Fields
Delete specific fields or sensitive data.
Remove: meta, debug, internal
3. Rename Keys
Rename fields from one path to another.
From: firstName → To: first_name
4. Map Array Items
Transform each item in an array using expressions.
Array: items
Expression: item.price * 1.1 // Add 10% markup
5. Filter Arrays
Keep only items matching a condition.
Array: items
Condition: item.status === 'active'
Use Cases
API Response Shaping
Transform raw API responses into the exact format your frontend needs. Pick specific fields, rename inconsistent keys, and filter out debug data.
Data Cleaning
Remove sensitive fields (passwords, tokens, debug info) from JSON data before logging or sharing.
Array Processing
Transform product catalogs, user lists, and other arrays with price markups, status filters, or batch updates.
Key Normalization
Convert camelCase to snake_case (or vice versa) across your entire JSON structure.
Nested Path Navigation
Work with deeply nested data using dot notation: user.profile.settings.theme
How to Use
- Paste JSON in the left editor
- Define rules using the Transform Rules panel
- See results live in the right editor
- Copy the output or download as JSON
Enable Auto-apply to see changes instantly as you build rules.
Pro Tips
- Combine rules in sequence for complex transformations
- Load examples to see common patterns
- Test with samples to verify your rules work as expected
- Use expressions in Map operations:
item.name.toUpperCase(),item.count + 1, etc.
Privacy & Performance
- 100% Client-Side — No data sent to servers
- Lightning Fast — Instant transformations
- Free to Use — No signup, no limits
- Auto-Save — Your work persists locally
Common Transformations
Remove API Metadata
Rules: [
{ type: "remove", path: "meta" },
{ type: "remove", path: "debug" }
]Rename User Fields
Rules: [
{ type: "rename", from: "firstName", to: "first_name" },
{ type: "rename", from: "lastName", to: "last_name" }
]Price Markup
Rules: [
{ type: "map", path: "items", expression: "{ ...item, price: item.price * 1.1 }" }
]Active Items Only
Rules: [
{ type: "filter", path: "items", condition: "item.status === 'active'" }
]FAQ
Q: Can I combine multiple rules?
A: Yes! Rules are applied in order. You can chain pick, remove, rename, map, and filter operations.
Q: How does Pick work with nested data?
A: Use dot notation. Pick: user.name, user.email, product.title extracts only those fields.
Q: What if a field doesn't exist?
A: The tool safely skips missing fields. No errors, no crashes.
Q: Can I save my rules?
A: Rules are auto-saved to your browser's local storage. Load them anytime.
Q: How large can JSON files be?
A: Most modern browsers handle several MB easily. Very large files (>50MB) may slow down the editor.
Developer Features
- No Dependencies — Pure JavaScript engine
- Expressions Support — Map arrays with custom JS expressions
- Deterministic — Same input + rules = same output, always
- Error Handling — Graceful error messages, never crashes
- Immutable — Original JSON never modified
Start transforming your JSON data now. It's free, fast, and entirely in your browser.