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JSONLab — Free Online JSON Viewer, Formatter, Validator & Converter

JSONLab is a fast, free and privacy-first online JSON workbench built for developers. It brings a complete set of json tools together in one clean, ad-free interface: a json viewer, a json formatter, a json validator, a json diff checker and a full json converter. Everything runs 100% in your browser, so your data never leaves your machine — paste a payload, format it, and you are done. No sign-up, no upload, no tracking.

View, edit and beautify your JSON

Drop any json file into the editor and explore it in a collapsible tree view. The built-in json editor lets you add, rename and delete keys, copy the exact JSON path of any node, and preview rich values like image URLs, colors and timestamps. The one-click json beautifier applies a clean json format with your choice of 2-space, 4-space or tab indentation, while the minifier strips whitespace for compact production payloads. Under the hood a strict json parser reads your data exactly as written, even for very large files. JSONLab doubles as a clean json tree viewer for quickly understanding the shape of unfamiliar API responses.

Validate JSON and fix syntax errors

The real-time json validator highlights syntax errors inline with precise line numbers and clear messages, so you can see at a glance when a quote, comma or bracket is wrong. Wondering about json syntax square brackets? In JSON, square brackets [ ] define an array (an ordered list of values) and curly braces { } define an object of key/value pairs. The smart fixer repairs the most common mistakes automatically — trailing commas, single quotes and unquoted keys. New to the format? A json file is simply plain text written in JavaScript Object Notation, which answers the common question what is a json file.

Compare and diff two JSON documents

Need to json compare two payloads? The semantic json diff engine understands structure, not just text, so reordered keys are correctly treated as identical. You see every real json difference side by side, can merge changes left-to-right, export a standard RFC 6902 patch, and even run a three-way merge to resolve conflicts between a base, left and right version.

Convert JSON to anything

The json converter turns your data into the format you need and back again: json to csv, json to yml / YAML, json to xml and TOML. The json to table grid view transforms an array of objects into a searchable, sortable spreadsheet. JSONLab also generates strongly-typed code straight from a sample, including json to java POJOs, json to go structs, TypeScript interfaces, Python dataclasses and Dart classes. For slicing large datasets, the built-in JSONPath and JMESPath query bar lets you filter and extract exactly what you want.

Compare plain text, not just JSON

Sometimes the two things you need to diff are not JSON at all. The Text Compare tool is a dedicated text diff that lets you compare text online line by line — paste two blocks of plain text on the left and right and every added, removed and changed line is highlighted side by side. It is ideal for logs, config files, prose, SQL or code snippets, with clickable arrows to jump between differences. Like every other tool here, it runs entirely in your browser, so nothing is uploaded.

Why developers choose JSONLab

JSONLab combines viewing, editing, validating, diffing and converting in a single keyboard-friendly app that stays fast even with 20MB+ files thanks to background web workers. It is ad-free, open in your browser, and built privacy-first — making it a modern alternative to cluttered legacy online json tools. Power users get fast keyboard shortcuts for formatting, clearing and collapsing nodes, plus shareable links that encode a payload directly in the URL — handy for sending a mock response to a teammate. Whether you need to quickly read an API response, debug a config file, beautify a minified blob, or run a one-off json compare, JSONLab handles it without installs or accounts. Bookmark JSONLab as your everyday JSON viewer, formatter and converter.

Frequently asked questions about JSON

What is a JSON file?

A JSON file (with a .json extension) is a plain-text file that stores structured data using JavaScript Object Notation. It is built from key/value pairs, arrays and nested objects, and is widely used for APIs, configuration and data exchange between applications. You can open and read any JSON file in JSONLab directly in your browser.

What is the difference between XML and JSON?

JSON and XML both store and exchange structured data, but JSON is lighter and easier to read. JSON uses key/value pairs with braces {} and arrays with brackets [], while XML wraps data in nested opening and closing tags. JSON maps directly to native data types (objects, arrays, numbers, booleans), is less verbose, and is faster to parse — which is why most modern web APIs prefer it. JSONLab can convert between JSON and XML in both directions.

How to open a JSON file?

The easiest way is to paste or drag the file into JSONLab — it opens instantly in your browser as a formatted, collapsible tree, with no upload. You can also open a .json file in any text editor (VS Code, Notepad, TextEdit) or drag it into a browser tab, but a dedicated JSON viewer makes it far easier to read and navigate.

What does JSON stand for?

JSON stands for JavaScript Object Notation. It is a language-independent data format that originated from JavaScript object syntax but is now supported by virtually every programming language.

What is JSON format?

JSON format is a set of simple rules for representing data as text. Objects are wrapped in curly braces {} and contain comma-separated "key": value pairs; arrays are wrapped in square brackets [] and hold ordered lists of values. Values can be strings, numbers, booleans, null, objects or arrays. Keys and string values must use double quotes. JSONLab validates and beautifies your data against these rules automatically.

How to create a JSON file?

Type or paste your data into the JSONLab editor, format it to confirm it is valid, then save or copy it into a file with a .json extension. Start from an object like { "name": "Ada", "active": true }, add the keys and values you need, and use the validator to catch any missing commas or quotes before you save.

How do I convert a JSON file to readable?

Paste the JSON into JSONLab and click Format (beautify). It re-indents the data with your chosen spacing and shows it as a collapsible tree, turning a single minified line into clean, readable structure. You can expand or collapse any object or array and copy the path to any value.

Can Chrome open JSON?

Yes. Chrome can display a .json file if you open it as a URL or drag it into a tab, but it shows raw, unformatted text. For a readable, collapsible, syntax-highlighted view with validation and search, open the file in JSONLab instead — it runs entirely in your browser, including Chrome.

What is a JSON viewer?

A JSON viewer is a tool that displays JSON data in a structured, easy-to-read way — typically a collapsible tree with syntax highlighting, type indicators and search — instead of raw text. JSONLab is a privacy-first online JSON viewer that also formats, validates, compares and converts JSON, all without uploading your data.

How to beautify JSON in Chrome?

Open JSONLab in Chrome, paste your JSON, and click Format to beautify it with proper indentation. Because everything runs client-side, you do not need a browser extension and your data never leaves the tab. You can switch indentation between 2 spaces, 4 spaces or tabs, or minify it again with one click.

How do I validate JSON and fix errors?

JSONLab validates as you type, highlighting syntax errors inline with the exact line and column. The built-in smart fixer can auto-repair common mistakes such as trailing commas, single quotes and unquoted keys, so you can turn broken JSON into valid JSON in one step.

How do I convert JSON to CSV, YAML or XML?

Open the Converter tool, paste your JSON, and choose the target format. JSONLab converts JSON to CSV, YAML, XML and TOML (and back again), and can generate typed code such as TypeScript interfaces, Java POJOs, Go structs, Python dataclasses and Dart classes from a sample.

How do I compare two JSON files?

Use the Diff Checker. Paste one document on each side and JSONLab runs a semantic comparison that ignores key order and formatting, so only real changes are highlighted. You can view differences side-by-side or unified, merge changes, and export a standard RFC 6902 JSON Patch.

How do I compare two blocks of text?

Use the Text Compare tool. Paste one block of text on each side and JSONLab highlights every added, removed and changed line side by side, so you can diff logs, config, prose or code snippets — not just JSON. Clickable arrows step you through each difference, and everything runs in your browser, so nothing is uploaded.

Is JSONLab free, and is my data private?

Yes. JSONLab is completely free and ad-free, and every feature — viewing, formatting, validating, diffing and converting — runs 100% inside your browser. Your JSON is never uploaded to a server, so sensitive API payloads and logs never leave your machine.

Can JSONLab handle large JSON files?

Yes. JSONLab offloads parsing and comparison to background web workers, so the interface stays responsive even with large files (20MB+) that would freeze many other online viewers.