What does the TOON Viewer tool do?

TOON Viewer allows developers to inspect, validate, format, search, and convert TOON documents with real-time JSON preview, an interactive node tree explorer, and live token savings estimates.

How does TOON reduce tokens for LLMs and AI agents?

TOON declares array headers once (e.g. `users[50]{id,name,role}:`) followed by comma-separated value rows, eliminating redundant repeated key names, quotation marks, and nested braces across hundreds of objects.

Is my data secure and private?

Yes. All parsing, validation, search, and JSON conversions occur entirely in your local browser using client-side JavaScript. Zero data is sent to external servers.

Can I convert JSON to TOON and TOON to JSON?

Yes. When you enter TOON, JSON is generated automatically. You can also upload existing `.json` files to convert them directly into compact TOON.

Online TOON Viewer | Tree Inspector | JSON Preview

TOON Viewer

View, syntax-highlight, inspect interactive node trees, and convert Token-Oriented Object Notation documents into clean JSON in real-time.

TOON Inspection & Conversion Workspace

Edit TOON syntax, review JSON preview, search keys, and explore hierarchical data structures.

TOON Inputtoon

Valid TOON

12 lines•318 chars•86 tokens•318 B

JSON Previewjson

{ "users": [ { "id": 1, "name": "Alice Johnson", "email": "alice@example.com", "role": "admin", "active": true }, { "id": 2, "name": "Ravi Sharma", "email": "ravi@example.com", "role": "editor", "active": true }, { "id": 3, "name": "Mina Tanaka", "email": "mina@example.com", "role": "viewer", "active": false } ], "meta": { "version": 2.1, "source": "api.users.v2", "environment": "production" }, "settings": { "max_retry": 3, "timeout_ms": 5000, "tags": [ "auth", "billing", "admin" ] } }

{
  "users": [
    {
      "id": 1,
      "name": "Alice Johnson",
      "email": "alice@example.com",
      "role": "admin",
      "active": true
    },
    {
      "id": 2,
      "name": "Ravi Sharma",
      "email": "ravi@example.com",
      "role": "editor",
      "active": true
    },
    {
      "id": 3,
      "name": "Mina Tanaka",
      "email": "mina@example.com",
      "role": "viewer",
      "active": false
    }
  ],
  "meta": {
    "version": 2.1,
    "source": "api.users.v2",
    "environment": "production"
  },
  "settings": {
    "max_retry": 3,
    "timeout_ms": 5000,
    "tags": [
      "auth",
      "billing",
      "admin"
    ]
  }
}

Valid JSON Generated

39 lines•662 chars•186 tokens•662 B

Interactive Node Tree

Click nodes to expand/collapse • Hover to copy paths

6 Objects

2 Arrays

24 Keys

Depth: 4

$ (root) object

users array[3]{ 3 items }

meta object{ 3 keys }

settings object{ 3 keys }

Client-side TOON parsing & validation•Real-time syntax highlighting & tree exploration•Zero server transmission

AI & Prompt Engineering Tool

Online TOON Viewer, Inspector & Token Optimizer

Explore, debug, syntax-highlight, and convert Token-Oriented Object Notation (TOON) documents online. Inspect interactive node trees, calculate LLM prompt token savings, search matches with arrow navigation, and convert TOON to formatted JSON with zero server dependencies.

30-60% Token Reduction

Tabular array compression eliminates repeated JSON keys, dramatically cutting LLM API costs and prompt latency.

Real-Time JSON Preview

Instantly parse and convert TOON into standardized, formatted JSON side-by-side as you type or edit.

Interactive Node Tree

Navigate complex structures, inspect data types, search keys, and copy JSON paths (e.g. `$.users[0].email`) in one click.

100% Client-Side Privacy

No data is sent to external servers. All parsing, validation, and conversions happen completely in your local browser.

Why TOON Format

Why Use TOON and How It Solves LLM Prompt Inefficiencies

As AI models power modern applications, prompt costs and context window limits have become major architectural constraints. Here is why TOON has emerged as the premier token-efficient notation:

Built for AI Models, LLM Prompts & RAG

Large Language Models (like GPT-4o, Claude 3.5, Gemini 1.5, and Llama 3) bill per token. Standard JSON repeats the same key names hundreds of times across array items. TOON defines keys once in the header, saving massive context window space and lowering inference costs.

Tabular Compression with Hierarchical Depth

CSV is compact but cannot handle nested objects. JSON handles nested structures but wastes tokens on repetitive keys. TOON provides the best of both worlds: tabular rows for lists of objects combined with YAML-like indentation for nested trees.

Human-Readable & AI-Parseable

TOON was engineered to be effortlessly readable by human engineers and effortlessly generated/parsed by modern AI systems with minimal hallucination rates.

Fits Larger Datasets into Context Windows

By compressing payload size by up to 60%, developers can feed 2x to 3x more database rows, search results, and API payloads into single prompt context windows.

Tool Capabilities

Comprehensive Features of the TOON Viewer Workspace

Everything you need to inspect, validate, format, search, and transform Token-Oriented Object Notation.

Side-by-Side Dual Editor Workspace

Type, paste, or upload TOON files on the left and see formatted, syntax-highlighted JSON generated in real time on the right.

Interactive Hierarchical Tree Inspector

Collapsible and expandable nodes with color-coded type badges (object, array, string, number, boolean, null) and tree search filtering.

Search & Match Navigation

Find text, keys, or regex patterns with Up/Down arrow navigation, real-time match counters, and case-sensitive matching in both editors.

High-Contrast Syntax Highlighting

Colors calibrated for both light and dark themes to ensure maximum readability for code keys, numbers, booleans, and strings.

Live Token Savings & Metric Estimator

Real-time metrics tracking line counts, character counts, estimated LLM token usage, and payload sizes right in the editor footer.

Format, Minify & Syntax Validator

One-click beautifier and minifier with line-level diagnostics that pinpoint indentation errors, count mismatches, or invalid syntax.

Data Format Benchmark: TOON vs JSON vs YAML vs CSV

Compare token density, structure capability, human readability, and ideal use cases across popular formats.

Format	Token Density	Nested Structures	Tabular Arrays	Human Readability	Primary Use Case
TOON	★★★★★ (Ultra Low)	Full Support	Native (Header + CSV Rows)	High	LLM Prompts, RAG Datasets, AI Payloads
JSON	★★☆☆☆ (High Overhead)	Full Support	No (Repeats All Keys)	Standard	Web APIs, Storage, General Interchange
YAML	★★★☆☆ (Moderate)	Full Support	No (Dash Lists)	High	Configurations, CI/CD Pipelines, Kubernetes
CSV	★★★★☆ (Very Low)	None (Flat Only)	Native	Moderate	Spreadsheets, Flat Exports, Relational DBs

Syntax Specification

How TOON Syntax Works

Understanding the core syntax rules of Token-Oriented Object Notation:

1. Tabular Arrays of Objects

Declared as name[N]{field1,field2}: followed by N comma-separated value rows indented with 2 spaces.

2. Simple Inline & Multi-line Arrays

Inline arrays: tags[3]: a,b,c. Multi-line scalar arrays use bullet dashes: - value.

3. Key-Value Fields & Indentation

Key-value pairs use key: value. Nested objects are created with 2-space indentation levels.

4. Comments & Scalars

Comments start with #. Scalars automatically parse as numbers (123, 4.5), booleans (true/false), null (null), or strings.

Sample TOON Document

users[3]{id,name,email,role,active}:
  1,Alice Johnson,alice@example.com,admin,true
  2,Ravi Sharma,ravi@example.com,editor,true
  3,Mina Tanaka,mina@example.com,viewer,false
meta:
  version: 2.1
  source: api.users.v2
  environment: production
settings:
  max_retry: 3
  timeout_ms: 5000
  tags[3]: auth,billing,admin

Step-by-Step Guide

How to Use TOON Viewer in 4 Steps

Follow this simple workflow to inspect, validate, search, and convert TOON documents into clean JSON.

Paste or Upload

Paste your TOON text into the left editor, click the Upload icon, or drag and drop a .toon or .json file.

Live JSON Preview

Instantly view the parsed JSON structure in the right panel with synchronized line numbers and high-contrast syntax highlighting.

Search & Tree Inspect

Use Ctrl+F to navigate search matches with Up/Down arrows, and expand/collapse nested branches in the interactive Node Tree.

Copy & Export

Copy individual JSON paths, node values, or the full formatted output with one click, or download the result as .json.

Frequently Asked Questions

Common Questions About TOON & TOON Viewer

TOON (Token-Oriented Object Notation) is a compact, human-readable data format engineered specifically for AI prompts, LLM context windows, and API payloads. It combines the tabular compression of CSV for uniform arrays with YAML-like indentation for nested objects, slashing token consumption by 30% to 60% compared to standard JSON.

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