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TOON to JSON Converter

Real-time conversion from TOON to standard JSON format

JSON Indent Width
Path Expansion
Input TOON
JSON Output
Read-only

What is TOON to JSON Converter?

A free online tool for converting TOON (Token-Oriented Object Notation) format data to standard JSON format.

TOON is a new data format introduced in 2025, optimized for LLM (Large Language Model) prompts. It expresses the same information as standard JSON with 30-60% fewer tokens, helping reduce token costs when interacting with ChatGPT, Claude, and other LLMs. However, since most existing tools and APIs expect standard JSON format, converting from TOON to JSON is often necessary.

This tool instantly converts TOON format data output by LLMs into standard JSON that works with existing tools and APIs. All processing happens in your browser, so your data is never sent externally. Delimiters and indentation are automatically detected, and results can be copied with one click.

TOON Format Features

TOON specializes in representing tabular data with these characteristics:

  • Improved Token Efficiency: Reduces tokens by 30-60% compared to JSON by explicitly declaring array length [N] and field names {fields}
  • LLM Optimized: Explicit structure improves LLM parsing accuracy
  • Ideal for Tables: Highly effective for compressing data with consistent fields like employee lists or product catalogs
  • Reversible: Lossless conversion between JSON and TOON

Common Use Cases

  • Convert LLM responses to JSON for integration with existing systems and databases
  • Share efficiently stored TOON format data in a universal format with other developers
  • Restore and validate data previously converted with the JSON to TOON tool
  • Validate TOON format syntax and debug issues
  • Data conversion and testing during API development

How to Use

Paste your TOON data into the left input area, and the converted JSON will appear instantly on the right. The tool automatically detects delimiters and indentation, so you can simply paste and convert.

If there are syntax errors, a detailed error message will guide you through fixing them.

Supported Formats

The tool handles:

  • Delimiters: Automatically detects commas, tabs, and pipes
  • Indentation: Automatically detects 2/4/6/8 spaces
  • Key Folding: Supports dot notation for nested structures

Conversion Examples

Basic Conversion

TOON Input:

users[2]{id,name,role}:
  1,Alice,admin
  2,Bob,user

JSON Output:

{
  "users": [
    { "id": 1, "name": "Alice", "role": "admin" },
    { "id": 2, "name": "Bob", "role": "user" }
  ]
}

Key Folding (Dot Notation)

Nested structures in dot notation are correctly expanded.

TOON Input:

user.profile.name: Alice
user.profile.email: alice@example.com

JSON Output:

{
  "user": {
    "profile": {
      "name": "Alice",
      "email": "alice@example.com"
    }
  }
}

About TOON Format

TOON (Token-Oriented Object Notation) is a data format optimized for LLM prompts. It expresses the same information as standard JSON with 30-60% fewer tokens, making it particularly effective for tabular data compression.

Why Convert to JSON?

TOON excels in LLM interactions, but most existing tools and APIs expect standard JSON. This converter lets you:

  • Use LLM-generated TOON data in existing systems
  • Share TOON format data with other developers in a universal format
  • Switch between JSON and TOON based on your needs

Key Characteristics

  • High Token Efficiency: Expresses the same information with 30-60% fewer tokens
  • Tabular Optimization: Explicitly declares array length [N] and field names {fields}
  • Reversible Conversion: Lossless conversion between JSON and TOON

Learn More About TOON

TOON is a new format that emerged in 2025, with specifications being developed by the community.

For detailed specifications, benchmark results, and implementations in other programming languages, visit the official site: