JSON Explorer

JSON (JavaScript Object Notation) is a lightweight text format for storing and exchanging data. It uses key–value pairs inside curly braces {} for objects and square brackets [] for lists (arrays). It is the most common format for web APIs, configuration files, and data storage.

Example of valid JSON:
{"name": "Alice", "age": 30, "active": true}

JSON Explorer is a free, browser-based developer tool that gives you seven tools in one page: explore, diff, transform, insights, visualise, sensitive data scanner and a JWT decoder. Built by Ian Tweedie and hosted by Mightora.io. No account required, no data uploaded, completely free forever.

Yes, completely. All processing happens entirely in your browser using JavaScript. There is no backend server, no API that receives your data, and no analytics that capture your JSON content. You can safely paste API keys, passwords, tokens and confidential configuration files. Close the browser tab and the data is gone.

Paste your JSON into the input box and it is automatically formatted. To explicitly pretty-print or minify, switch to the Transform tab and click Pretty Print or Minify. You can also sort keys alphabetically and remove nulls in the same tab.

Switch to the Diff tab. Paste your original JSON in the left box and the modified version in the right box, then click Compare.

• ➕ Green — fields added in the right version
• ➖ Red — fields removed from the left version
• ∼ Orange — values that changed

Toggle “Show unchanged” to focus only on differences.

JSON flattening converts a deeply nested object into a single-level object where keys are separated by dots to show the path. For example {"user":{"name":"Alice"}} becomes {"user.name":"Alice"}. Use the Flatten button in the Transform tab. Use Unflatten to reverse it.

A JWT (JSON Web Token) is a compact, URL-safe string with three dot-separated parts: a header, a payload and a signature. It is used to pass identity information (claims) between systems.

Switch to the Sensitive Data tab and scroll to the JWT Decoder panel. Paste your JWT token and click Decode to see the header and payload. Note: signatures are not verified — the tool just reads the encoded data.

Switch to the Sensitive Data tab after pasting your JSON. The scanner automatically flags fields whose names suggest sensitive content — such as password, token, apiKey, secret, email and many more. Each finding shows a severity level (high / medium / low) and an explanation. Use the Mask values toggle to blur the actual values before sharing a screenshot.

Once the page has loaded in your browser, all seven tools work without an internet connection. Only the initial page load requires connectivity (to fetch fonts, icons and Chart.js). There is no server communication once the page is open.

The Upload button and drag-and-drop accept .json and .txt files. Any text file that contains valid JSON will work. Maximum practical file size depends on your browser and device memory.

Common JSON mistakes:

• Trailing comma — remove the last comma before } or ]
• Single quotes — JSON requires double quotes around strings and keys
• Unquoted keys — write "name" not name
• Missing comma — add commas between all items in an array or object
• Comments — standard JSON does not support comments (// ... or /* */)

When the error is auto-fixable, a Auto-repair button appears below the input.

Switch to the Visualise tab after pasting your JSON. JSON Explorer auto-detects the best chart type:

• Arrays of objects with a date field → line chart (time series)
• Arrays of objects with a string + number field → bar chart
• Arrays of strings → pie chart (frequency)
• Objects with numeric values → bar chart

Use the dropdown to switch to Table, Nested Boxes or Structure Tree at any time. Tables can be exported as CSV.

The Nested Boxes view (in the Visualise tab) shows your JSON as a set of colour-coded nested containers — one box per object or array, with each depth level getting a different colour. This makes it very easy to see the structure and hierarchy of your data at a glance, even without reading the actual values.

It is especially useful for understanding deeply nested API responses or configuration files where the shape of the data matters more than the values.