Free Online JSON Editor — Format and Validate JSON

Format, validate, compress, and edit JSON online. No signup, no upload — your data stays on your device, 100% private and secure.

How to Use DataPad JSON Editor

Open the JSON editor — just visit this page, no signup needed.
Load your JSON — drag and drop a .json file, paste JSON text, or load our sample data to get started.
Edit in the left pane — real-time syntax highlighting and line numbers help you navigate your data.
View formatted output — the right pane shows your JSON beautifully formatted with automatic error detection.
Use the tools — format with 2 or 4 spaces, compress to single line, sort keys alphabetically, or copy the result.
Export your file — download as .json or save back to the original file on your hard drive.

Key Features

Real-time dual-pane editor — edit raw JSON on the left, see formatted output on the right, with line numbers on both panes.
Precise error detection — syntax errors are highlighted with exact line and column numbers. No more guessing where the problem is.
Format and compress — switch between 2-space and 4-space indentation, or compress your JSON to a single line.
Sort keys alphabetically — recursively sort all object keys at every nesting level for consistent output.
Multiple import methods — upload .json files, drag and drop, paste JSON text, or start with a blank template.
Export and save back — download formatted JSON or save changes directly back to the original file using File System Access API.
100% private and secure — all processing happens locally in your browser. Files are never uploaded to any server.
Undo / Redo — full undo history so you can experiment confidently.

JSON vs CSV — What Is the Difference?

Feature	JSON	CSV
Data structure	Hierarchical (objects, arrays)	Flat tabular (rows and columns)
Data types	String, number, boolean, null, object, array	All values are text
Best for	APIs, configuration, nested data	Spreadsheets, data exchange, databases
Human readability	Good (with formatting)	Poor (hard to read unformatted)
File size	Larger (includes field names)	Smaller (compact)
Schema	Optional (JSON Schema)	No built-in schema

Frequently Asked Questions

Is this JSON editor free?

Yes, DataPad is completely free to use. No signup, no subscription, no hidden fees.

Do I need to sign up or install anything?

No. You can start editing immediately in your browser. There is nothing to install, no account required.

Is my data uploaded to a server?

No. All file processing happens locally in your browser. Your data never leaves your device.

How do I format JSON online?

Simply paste your JSON into the left pane. The right pane automatically shows the formatted version. Use the toolbar to switch between 2-space and 4-space indentation.

How do I validate JSON?

As you type, DataPad validates your JSON in real-time. Syntax errors are highlighted with the exact line and column number so you can fix them quickly.

Can I compress JSON to one line?

Yes. Click the "Compress" button in the toolbar and your JSON will be minified to a single line with no whitespace.

What does "Sort Keys" do?

Sort Keys recursively sorts all object keys alphabetically at every nesting level. This is useful for diffing JSON files or ensuring consistent output.

How do I save my JSON file?

You can download your JSON by clicking Export, or use "Save Back to File" to write changes directly back to the original file using the File System Access API.

Can I edit large JSON files?

DataPad can handle JSON files up to 500KB or 10,000 lines smoothly. A warning is shown for larger files as they may impact performance.

What JSON types are supported?

JSON supports strings, numbers, booleans, null, objects (key-value pairs), and arrays. The sample data demonstrates all six types.