Advanced JSON Toolkit: Free Online JSON Viewer & Formatter
A free, private, browser-based JSON viewer and formatter. Paste or upload JSON to validate, beautify, minify, and explore it as an interactive tree — nothing ever leaves your device.
How do I format and view JSON online?
Three steps, no sign-up, nothing installed — and your data never leaves the browser.
Add your JSON
Paste JSON into the editor, drag & drop a .json file, upload one, or fetch it straight from an API URL. Validation runs instantly as you type.
Format it
Click Beautify for readable, 2-space-indented pretty print, or Minify to strip every unnecessary character for production payloads.
Explore & export
Browse the interactive tree, switch to table view for arrays, search any key or value, click a node to copy its path, then copy or download the result.
Everything you need to work with JSON
Beautify
Reformat JSON with clean, consistent indentation.
Minify
Strip whitespace for the smallest possible payload.
Tree view
Explore nested JSON with expand and collapse controls.
Table view
View any array of objects as a sortable, scannable spreadsheet.
Search
Find any key or value instantly, anywhere in the document.
Upload files
Drag & drop or upload .json files up to 10MB.
Load from URL
Fetch JSON directly from an API or file URL.
100% private
Everything runs client-side — your data never leaves your browser.
Common JSON errors and how to fix them
Paste your JSON above to pinpoint the exact line — then match the error message here.
Unexpected token ' (single quote)
Cause: JSON strings and keys must use double quotes.
Fix: Replace 'value' with "value". The validator above points to the exact line and column.
Unexpected token } or ] (trailing comma)
Cause: JSON forbids a comma after the last item in an object or array.
Fix: Remove the final comma: {"a": 1,} becomes {"a": 1}.
Unexpected end of JSON input
Cause: The document is truncated — usually a missing closing brace/bracket or a copy-paste that got cut off.
Fix: Re-copy the full payload, then balance every { with } and every [ with ]. Beautify makes unbalanced nesting easy to spot.
Unexpected token / in JSON
Cause: Comments (// or /* */) are not part of the JSON standard.
Fix: Delete the comments. If you control the source, keep comments in code, not in the JSON itself.
Bad control character in string literal
Cause: A raw newline or tab inside a string — JSON strings must escape control characters.
Fix: Escape them: use \n for newlines and \t for tabs inside string values.
Frequently asked questions
Is this JSON viewer free to use?
Yes. The Advanced JSON Toolkit is completely free, with no sign-up, no ads, and no usage limits beyond the 10MB file size handled per session.
Does my JSON data get uploaded to a server?
No. Every operation — parsing, formatting, searching, and rendering the tree or table view — runs entirely in your browser. Your JSON never leaves your device.
How do I validate JSON online?
Paste your JSON into the editor (or upload a .json file) and it is validated instantly as you type. If the JSON is invalid, you'll see the exact error message with the line and column where parsing failed.
How do I fix an 'Unexpected token' or 'Unexpected end of JSON input' error?
Paste the JSON into the validator to see the exact line and column of the problem. The most common causes are: single quotes instead of double quotes, a trailing comma after the last item, a missing closing bracket or brace, comments (JSON doesn't allow them), or a truncated file.
Why is my JSON valid in JavaScript but invalid here?
JavaScript object literals are more permissive than JSON. JSON requires double-quoted keys and strings, forbids trailing commas and comments, and doesn't support undefined, NaN, or Infinity. This tool follows the official JSON standard (RFC 8259), which is what APIs and parsers expect.
What is the difference between beautify and minify?
Beautify (also called pretty print) reformats JSON with consistent 2-space indentation and line breaks so it's easy to read. Minify strips all unnecessary whitespace to produce the smallest possible payload for production use.
How do I pretty print JSON?
Paste your JSON and click Beautify. The document is reformatted with 2-space indentation and one property per line — the standard pretty-print style. Click Copy or Download to take the result with you.
Can I search inside deeply nested JSON?
Yes. The search box matches both keys and values anywhere in the document, automatically expands the tree to reveal every match in context, and shows a match counter with previous/next navigation.
Can I view a JSON array as a table?
Yes. Switch to table view (next to the search box) whenever an array of objects — like an API response list — is loaded or selected in the tree. Each key becomes a column, making the data much easier to scan than a nested tree.
Can I load JSON directly from a URL instead of pasting it?
Yes. Use the "Load URL" button (or the command palette) to fetch JSON straight from an API or file URL in your browser. This works for same-origin or CORS-enabled endpoints; some third-party APIs block cross-origin requests entirely.
What's the maximum file size I can upload?
You can upload or paste JSON files up to 10MB in size.
Is it safe to paste sensitive JSON like API responses with tokens?
Everything is processed locally in your browser and never transmitted, so pasting sensitive data here is far safer than using server-based formatters. As a general habit, still redact secrets before sharing JSON anywhere outside your machine.
Does this JSON formatter work offline?
Once the page has loaded, all core features — validate, beautify, minify, tree view, table view, and search — run without a network connection, because nothing is sent to a server. Only the "Load from URL" feature needs internet access.
Does it work on mobile?
Yes. The layout is fully responsive: on phones the editor and tree stack vertically with a draggable divider, and all actions remain available from the toolbar.
What is the difference between JSON and XML?
Both are text formats for exchanging data. JSON is lighter, maps directly to data structures in most programming languages, and has become the default for web APIs. XML is more verbose but supports attributes, namespaces, and schema validation, and remains common in enterprise and document-centric systems.