JSON to TOON Converter

The JSON to TOON Converter instantly transforms standard JSON data into TOON (Token-Oriented Object Notation) — a modern, tokenized data format designed for readability, compactness, and machine efficiency. It also lets you customize how TOON is encoded with indentation, key folding, and delimiter options.

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

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 JSON, the tool parses it into an abstract syntax tree (AST) and serializes that structure into TOON tokens. Arrays, objects, and primitives are mapped into ordered, self-descriptive tokens using the @toon-format/toon library.

All processing happens locally — no upload required. You can also copy the resulting TOON code or compare its size and token efficiency directly in the result table.

The converter provides advanced controls for customizing how TOON output is formatted:

• Indentation: Controls how many spaces per level are used in nested data. Choose between 0 (compact), 2, or 4 spaces for better readability.
• Key Folding: Collapses objects with single nested keys into a shorter dotted form (e.g. data.metadata.items instead of nested indentation). 'Safe' mode ensures readability without flattening complex structures.
• Delimiter: Defines how array elements and inline values are separated (comma, semicolon, or pipe). Useful for aligning with other serialization styles.
• Allow Duplicates: Keeps repeated keys intact in TOON output if your input data includes them intentionally.

These parameters let developers fine-tune TOON output for compactness, compatibility, or readability depending on the use case.

• Compactness: Removes redundant syntax and quotes, reducing size up to 70%.
• Extensibility: Supports annotations and metadata for richer structures.
• Speed: Easier to parse for both humans and machines.
• Customization: Adjustable indentation, key folding, and delimiters.
• Interoperability: Designed to coexist with JSON pipelines.

// JSON
{
  "user": { "name": "Alice", "age": 25 }
}

// TOON (safe folding + comma delimiter)
user{name,age}: Alice,25