How to view JSON online
- Paste your JSON into the editor on the left, drop a file onto it, or press Open.
- Explore the result in the Tree tab, search keys and values, and copy any value or path.
- Press Format (Ctrl+Enter) to beautify it with 2 or 4 spaces, or Minify to compact it.
- Use Copy Output or Download to take the formatted JSON with you.
What can you do with the JSON viewer?
Paste JSON, drop a file onto the editor or press Open, and the tree view shows the structure instantly. Click any object or array to expand or collapse it, use Expand and Collapse to open everything or fold it back to the first level, and search keys and values at the same time. Hover a row to copy its value or its path, for example $.users[0].address.city, ready to paste into code.
Tree view or formatted text?
The Tree tab is best for exploring: it shows types by colour, counts the children of every node and lets you jump to what you need. The Formatted tab shows the same data as indented text with 2 spaces, 4 spaces or compact output, and optional alphabetical key sorting. Use Format to write the pretty version back into the editor, or Minify to compress it.
Understanding the colours and types
Strings are shown in orange, numbers in green, booleans in blue and null in purple, so a value of the wrong type stands out at a glance. A number written as a string, such as "42", keeps its quotes and its string colour, which is one of the quickest ways to spot a data-type bug in an API response.
Working with API responses
Copy a response from your browser's network tab, curl output or a log line and paste it in. If the text contains single quotes, comments or trailing commas, press Fix JSON. Use the status bar to see the size, depth and number of nodes, which helps you estimate how heavy a payload is before it reaches production.
Tips for very large JSON files
Collapse everything first and expand only the branch you care about. Search narrows the tree to matching paths, which is faster than scrolling through hundreds of thousands of rows. For files above a few megabytes the editor automatically switches to a lighter mode, but parsing and the tree stay responsive because they run off the main thread.
A viewer built for large files
Most online formatters freeze on big payloads because they render every node. This tool parses in a background thread and virtualizes the tree, drawing only the rows on screen, so multi-megabyte API dumps and exports stay responsive. Search matches keys and values and opens the path to each hit.
Private by design
There is no upload step and no backend. Your JSON is processed by JavaScript running in your own browser tab, so tokens, customer records or internal configuration never reach a third-party server. You can verify this in your browser's network tab.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based data format that is easy for people to read and for machines to parse. It is the de facto standard for web APIs, configuration files and data exchange between services. A JSON document is built from just six value types: objects, arrays, strings, numbers, booleans and null.
{
"name": "Ada",
"age": 36,
"admin": true,
"skills": ["math", "code"],
"address": { "city": "London" },
"manager": null
}JSON is stricter than JavaScript object literals: keys and strings must use double quotes, trailing commas are not allowed and comments are not part of the specification (RFC 8259).
Why format JSON?
APIs usually return minified JSON on a single line, which is efficient for machines but unreadable for people. Formatting (also called pretty printing or beautifying) adds consistent indentation and line breaks so that you can scan the structure, spot mistakes and review changes. Minifying does the opposite and strips whitespace to reduce size.
Frequently asked questions
How do I fix invalid JSON?
Press Fix JSON. It repairs common problems such as single quotes, unquoted keys, trailing commas, comments and missing brackets. If something remains broken, the status bar and Go to error button point to the exact line and column.
Is my JSON uploaded to a server?
No. Parsing, validation, formatting, diffing and code generation all run inside your browser, using a Web Worker. Your data is never sent to any server, which makes the tool safe for API responses, configuration files and other sensitive payloads.
How large a JSON file can I open?
Files of 20 MB and more work. Parsing happens off the main thread and the tree view is virtualized, so only the rows you can see are rendered. The editor switches to a lighter mode for very large documents.
What is the difference between formatting and minifying JSON?
Formatting (pretty printing) adds line breaks and indentation so people can read the data. Minifying removes all optional whitespace to make the payload as small as possible for network transfer or storage. Both produce identical data.