TOON to JSON Converter

The TOON to JSON Converter instantly transforms TOON (Token-Oriented Object Notation) data back into standard JSON — the most widely used data interchange format. Decode compact, token-based TOON structures into well-formatted, readable JSON with customizable indentation.

This browser-based tool runs entirely locally and shows a detailed comparison between TOON and JSON, including token count and size differences.

TOON stands for Token-Oriented Object Notation — a human-readable, JSON-inspired syntax that represents structured data as an ordered list of tokens. It minimizes repetition and enables flexible extensions for typed data, annotations, and metadata.

TOON is open-source and defined at github.com/toon-format/toon.

When you paste TOON data, the tool uses the decode function from the @toon-format/toon library to parse the token stream and reconstruct the original data structure. The result is then serialized into standard JSON with your preferred indentation level.

All processing happens locally in your browser — no data is uploaded or sent to any server. You can copy the resulting JSON or compare its size with the original TOON input.

The converter provides indentation options to control how the JSON output is formatted:

• No Indentation: Produces compact, single-line JSON — ideal for API payloads and data transfer where size matters.
• 2 Spaces: The most common formatting style, balancing readability with compactness. Default in many modern editors and tools.
• 4 Spaces: Maximum readability for deeply nested structures. Preferred in some coding standards and documentation.

Choose the indentation level that best fits your workflow and downstream tools.

This converter is useful in several scenarios:

• Debugging: Inspect TOON data by converting it to the familiar JSON format for easier analysis.
• Integration: Convert TOON output from other tools back into JSON for use with APIs, databases, or applications that expect JSON.
• Learning: Understand TOON format by seeing how it maps back to JSON structures.
• Validation: Verify that TOON encoding preserved the original data structure by round-tripping through both converters.

While both formats represent structured data, they differ in key ways:

Use the TOON to JSON converter together with the json-to-toon to perform round-trip conversions. This is useful for:

• Verifying data integrity after encoding
• Testing TOON encoding configurations
• Understanding how different TOON settings affect the output
• Comparing data before and after conversion

The TOON format is designed for lossless round-trip conversion — converting JSON to TOON and back should produce equivalent data structures.

// TOON Input
name: Alice
age: 25
hobbies[2]: coding,music

// JSON Output
{
  "name": "Alice",
  "age": 25,
  "hobbies": ["coding", "music"]
}