TOON (Token-Oriented Object Notation) is a compact, human-readable format for serializing JSON data that minimizes tokens when working with Large Language Models. It achieves 30-60% token savings compared to JSON.

When should I use TOON instead of JSON?

Use TOON for uniform arrays of objects with consistent structure, especially large datasets. JSON is better for non-uniform data and deeply nested structures with varying field sets.

JSON to TOON Converter - Free Online Tool

Convert JSON to TOON Format

Optimize your LLM prompts with 30-60% token reduction. Free, instant, client-side conversion with real-time cost analysis.

✓ No Server Upload ✓ Real-time Token Analysis ✓ Cost Calculator

JSON Input

⚙️ Configuration

Delimiter

Indent

Show length markers [N]

Token Price ($/1K tokens)

TOON Output

# Your TOON output will appear here...
# Click "Convert" or type to see real-time conversion

📊 Token Analysis

JSON Tokens

TOON Tokens

Tokens Saved 0

Reduction 0%

Cost Saved $0.000

What is TOON?

🚀

30-60% Token Reduction

TOON eliminates redundant syntax like braces and quotes, achieving significant token savings for LLM prompts.

💡

Perfect for APIs

Optimized for uniform arrays of objects. Ideal for GPT, Claude, Gemini, and other LLM APIs with token pricing.

📊

Human-Readable

Combines YAML-style indentation with CSV-style tables, making it easy for both humans and LLMs to parse.

TOON vs JSON: Feature Comparison

Understanding the differences and when to use each format

Feature	TOON	JSON
Token Efficiency	High (30-60% savings)	Baseline
Human Readability	Excellent	Excellent
Uniform Arrays	Optimized	Verbose
Deep Nesting	Moderate	Better
Non-Uniform Data	Not Ideal	Perfect
API Support	LLM-Specific	Universal
Learning Curve	5 minutes	Already known
Use Case	LLM prompts & responses	Web APIs & storage

💡 Key Takeaway: TOON and JSON are complementary. Use JSON for application logic and APIs, then convert to TOON specifically for LLM interactions to save tokens and costs.

How to Use This JSON to TOON Converter

Paste or Upload JSON Data

Copy your JSON and paste it into the input field, or drag and drop a .json file directly into the converter.

Configure Conversion Options

Choose your delimiter (comma, tab, or pipe), indentation style, and toggle length markers to customize the output format inside JSON to TOON converter canvas.

Convert and Analyze

Click the Convert button to transform your JSON into TOON format. View real-time token analysis and cost savings.

Copy or Download

Use the Copy button to paste the TOON output directly into your LLM prompts, or download as a .toon file for later use.

Frequently Asked Questions About JSON to TOON Conversion

Everything you need to know about TOON format and this converter

What is TOON and why should I use it for LLM optimization?

TOON (Token-Oriented Object Notation) is a data serialization format specifically designed to reduce token usage when working with Large Language Models like GPT-4, Claude, and Gemini. It achieves 30-60% reduction in token usage compared to standard JSON by eliminating redundant syntax.

You should use TOON when:

Sending large datasets to LLM APIs where you pay per token (OpenAI, Anthropic, Google)
Working with uniform arrays of objects like user lists, product catalogs, or analytics data
Building AI applications where context window limits are a constraint
Optimizing prompt engineering workflows for cost efficiency and performance
Processing tabular data with consistent field structures

How does TOON reduce tokens compared to JSON?

TOON eliminates redundant syntax that inflates token counts in JSON through several optimization techniques:

Removes curly braces - Eliminates {} around objects, saving 2 tokens per object
Eliminates quotes around keys - Keys appear as name instead of "name"
Declares field names once - For arrays, fields are listed once in the header: users[100]{id,name,role}:
Uses CSV-style rows - Data flows in comma-separated values without repeating keys for each record
Indentation for nesting - YAML-style indentation replaces nested braces and brackets

Benchmarks show TOON achieves 73.9% model accuracy vs JSON's 69.7% while using 39.6% fewer tokens, resulting in significant API cost savings.

Does TOON work with GPT-4, Claude, Gemini, and other LLMs?

Yes! TOON is model-agnostic and works with any Large Language Model that processes text-based structured data, including:

✓ OpenAI Models - GPT-3.5, GPT-4, GPT-4 Turbo, GPT-4o

✓ Anthropic Claude - Claude 3 Opus, Sonnet, Haiku

✓ Google Gemini - Gemini Pro, Gemini Ultra

✓ Open-source LLMs - Llama 2, Llama 3, Mistral, Mixtral

Since TOON is a structured text format, any model capable of understanding structured data can parse it. Some developers report even better accuracy with TOON because it reduces syntactic noise that can confuse token-based models.

When should I NOT use TOON format?

TOON is optimized for specific use cases. Stick with standard JSON when you have:

Deeply nested structures (5+ levels) - JSON handles complex hierarchies more efficiently than TOON's indentation-based approach
Non-uniform arrays - Objects with varying fields don't benefit from TOON's tabular CSV-style format
Very small datasets - For single objects or small arrays (1-5 items), the token savings are negligible
Machine-to-machine REST APIs - TOON is designed for LLM inputs, not traditional web service APIs
Mixed data types in arrays - Arrays containing both objects and primitives lose TOON's structural advantages
Dynamic schema requirements - When field structures change frequently between requests

💡 Pro tip: Use our free converter to test your actual production data. The real-time token analysis will show if TOON provides meaningful savings for your specific use case.

How much money can I save using TOON with LLM APIs?

Cost savings depend on your API usage volume and data structure. Here are real-world examples based on current LLM API pricing:

Small Application (Startup) ~$50/month*

1,000 API calls/month with 100 records each. At $0.03/1K tokens (GPT-4 pricing), save approximately $50/month with TOON.

Medium Application (Growing SaaS) ~$300/month*

10,000 API calls/month with analytics data. At GPT-4 Turbo pricing, save approximately $300/month.

Enterprise Application $1,000+/month*

High-volume data processing with large datasets. Savings scale linearly with usage across OpenAI, Anthropic, and Google APIs.

With around 50%* reduction in token usage, if you're spending $1,000/month on LLM API calls, you could save $300-600 monthly just by converting JSON to TOON format for your prompts.

Is this JSON to TOON converter safe and private?

100% safe and private. This converter runs entirely in your browser using client-side JavaScript. We never:

Send your JSON or TOON data to any server or third party
Store, log, track, or analyze your conversion data
Use analytics, cookies, or third-party tracking scripts
Require account creation, login, or email addresses

🔒 Privacy First: Your conversion history is stored only in your browser's localStorage. You can clear it anytime from the History modal, and it never leaves your device.