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Quick Start

How to Use the JSON Formatter

A step-by-step guide to get the most out of every feature - from basic formatting to converting JSON into production-ready TypeScript, Java, or Go code.

  1. Paste or Upload your JSON

    Type directly into the Input editor, paste with Ctrl+V, click Smart Paste to pull from your clipboard automatically, or drag-and-drop a .json file (up to 5 MB) onto the page.

  2. Format or Minify

    Click Format to beautify with 2- or 4-space indentation. Click Minify to compact it for APIs or storage. Use the indent toggle (2 / 4 buttons) to switch indent size at any time.

  3. Validate & fix errors

    Errors are highlighted live with exact line and column numbers. Click Fix JSON to automatically repair trailing commas, single-quoted strings, unquoted keys, and other common issues.

  4. Explore with Tree View

    Switch to Tree View to navigate deeply nested structures. Expand or collapse any node with a click. Use the search box to instantly filter keys and values across the entire document.

  5. Convert to your language

    Click TypeScript, Java, or Go in the toolbar. The converter generates interfaces, POJOs (with Jackson annotations), or structs (with JSON tags) from your JSON schema - no extra tools needed.

  6. Copy, Download, or Save

    Copy the formatted output to clipboard with one click. Download a clean formatted.json file. Your JSON is also auto-saved to localStorage so your work survives a page refresh.

Everything Included - 100% Free

Monaco Editor
The same editor powering VS Code - with syntax highlighting, bracket matching, code folding, and a full JSON language server.
JSON Repair
Powered by jsonrepair - fixes trailing commas, JavaScript-style comments, single-quoted strings, unquoted keys, and more.
Tree Explorer
Navigate any JSON document visually. Collapse large arrays, search across keys and values, and highlight matches in context.
Code Converters
Generate TypeScript interfaces, Java POJOs with @JsonProperty annotations, or Go structs with `json:"..."` tags in one click.
Smart Paste
Reads your clipboard and auto-detects if it contains JSON. Valid JSON is pasted and formatted instantly - no extra steps.
File Upload
Drag and drop or click to upload any JSON file up to 5 MB. The content is loaded directly into the editor without any server upload.
Session Persistence
Your last JSON is saved to localStorage. Close the tab or refresh the page and your work is still there when you come back.
Stat Bar
Live character count, total key count (across all nesting levels), and estimated file size - updating as you type.

Frequently Asked Questions

Is my JSON data safe?
Yes. All processing happens entirely in your browser using JavaScript. No data is ever sent to a server. Your JSON never leaves your device.
What is the maximum file size?
The upload limit is 5 MB. For larger files, the Monaco editor can still handle them if you paste the content directly - it is optimised for performance on large inputs.
What does Fix JSON actually repair?
Trailing commas, single-quoted strings, unquoted property keys, JavaScript comments (// and /* */), missing closing brackets, and extra tokens at the end of the document.
How accurate are the TypeScript/Java/Go converters?
They perform a single-pass type inference. Nested objects produce their own interfaces/classes/structs. Arrays infer type from the first element. For production use, always review the output.
Does Tree View work on large JSON files?
Yes. Nodes are rendered lazily and only expanded on demand, so even documents with thousands of keys remain responsive. Use the search box to jump straight to the node you need.
Can I use this tool offline?
The Monaco editor bundle is fetched once and cached by the browser. After the first load, the formatter, validator, and tree view all work without an internet connection.

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