TOON to JSON Converter - Convert TOON to JSON Online

Input

Output

What is TOON to JSON Converter?

Need to convert your TOON (Token-Oriented Object Notation) data back to standard JSON (JavaScript Object Notation)? This tool does that instantly. TOON is a compact text format for passing structured data to LLMs, but most tools, APIs and validators still expect JSON.

The converter decodes TOON with the official @toon-format/toon library and pretty-prints the JSON. Tabular blocks like orders[2]{id,sku}: become arrays of objects, and integers too long for a JavaScript number (a 19-digit ICCID, say) are written with every digit instead of being rounded. Learn more about JSON at MDN.

Everything happens in your browser – your data stays private. Convert, download, and use your JSON right away. You can also validate your TOON first using our TOON Validator or format it with our TOON Formatter.

What Makes This Tool Different

Lossless Conversion

Objects, arrays, tabular rows, strings, numbers, booleans and null all come back as the matching JSON, and long integers keep every digit.

Instant Processing

Conversion happens in milliseconds. Paste your TOON, and get formatted JSON instantly. No waiting, no server delays – pure browser-side processing.

Pretty Formatted Output

The JSON output is beautifully formatted with proper indentation (2 spaces) and line breaks. Easy to read, easy to debug, ready to use.

File Upload Support

Got a TOON file? Just upload it. Works with .toon and .txt files. No need to copy-paste – just drag and drop or click upload.

Download JSON

One click to download your converted JSON as a .json file. Perfect for saving, sharing, or importing into other tools and systems.

Error Detection

Invalid TOON syntax? We'll show you exactly what's wrong. Clear error messages help you fix issues quickly before converting.

How It Works

Paste or Upload TOON

Paste your TOON data into the left editor, or click "Upload" to load a file. You can also click "Sample" to see example TOON format. The tool accepts any valid TOON structure – arrays, objects, nested data, tabular data.

Automatic Conversion

As soon as you paste, the converter processes your TOON and displays the converted JSON on the right. The conversion is instant and preserves all your data structure, types, and values perfectly.

Copy or Download

Use "Copy" to grab the JSON for pasting, or "Download" to get it as a .json file. The JSON is properly formatted and ready to use in any JSON-compatible tool or system.

When You'd Actually Use This

LLM Integration

Working with LLMs that output TOON format? Convert it back to JSON for integration with your existing APIs, databases, or frontend applications that expect standard JSON.

API Compatibility

Need to send data to APIs that only accept JSON? Convert your TOON data to JSON format for seamless integration with REST APIs, GraphQL endpoints, or web services.

Tool Compatibility

Many development tools, validators, and formatters only work with JSON. Convert TOON to JSON to use these tools while still benefiting from TOON's token efficiency when working with LLMs.

Data Sharing

Sharing data with team members or systems that don't support TOON? Convert to JSON for universal compatibility. Everyone can work with JSON, making collaboration easier.

Common Questions

Is my TOON data stored?

No. All conversion happens in your browser using the @toon-format/toon library. Your data never leaves your computer. The TOON library is available on npm for use in your projects.

What TOON formats are supported?

Everything the TOON library decodes: nested objects, inline arrays like tags[3]: a,b,c, tabular arrays with a {field,list} header, list items, and comma, tab or pipe delimiters. Row counts in headers are checked, so a header that says [3] with two rows is an error.

Can I convert invalid TOON?

No. The converter validates your TOON first. If it's invalid, you'll see an error message. Fix the syntax error, then convert again. Use our TOON Validator to check your TOON first.

Is the conversion lossless?

For values, yes. Every string, number, boolean, null, object and array becomes the equivalent JSON, and integers past JavaScript's 2^53 limit are written with their exact digits. JSON has no tabular form, so tables become arrays of objects; that's a change of layout, not of data.

How big can my TOON file be?

Since processing happens in your browser, performance depends on your device. Small files convert instantly. Very large files (10MB+) might take a few seconds, but they'll still work.

Why would I use TOON instead of JSON?

TOON is mainly useful inside LLM prompts, where uniform lists of records take fewer tokens than the same JSON. Outside that, JSON is what tools, APIs and databases understand, which is why this converter exists.

Other TOON Tools You Might Need

Converting TOON to JSON is just one TOON task. Here are other tools that work well together: