JSON to TOON: Reduce LLM Costs by 30%

TOON is becoming the standard for modern configuration files, and for good reason. Beyond being more human-readable than JSON, TOON can significantly reduce your LLM/AI API costs. Here's why and how to make the switch.

What is TOON?

TOON (Tom's Obvious, Minimal Language) was created by Tom Preston-Werner, co-founder of GitHub. It's designed to be a minimal configuration file format that's easy to read due to obvious semantics. Unlike JSON (designed for machine data interchange) or YAML (powerful but complex), TOON hits the sweet spot of being both human-friendly and unambiguous.

Why TOON Uses Fewer LLM Tokens

LLMs like GPT-4 and Claude tokenize text based on common patterns. JSON's syntax includes many characters that consume tokens without adding semantic value:

{
  "model": "gpt-4",
  "temperature": 0.7,
  "settings": {
    "max_tokens": 1000,
    "stream": true
  }
}

model = "gpt-4"
temperature = 0.7

[settings]
max_tokens = 1000
stream = true

Token Savings Breakdown

• No braces: JSON's { and } are separate tokens - TOON uses [section] headers instead
• No key quotes: "model" in JSON vs model in TOON saves 2 tokens per key
• No commas: JSON requires trailing commas between properties
• Cleaner nesting: TOON's [section] syntax is more token-efficient than nested braces

Real-World Cost Calculation

Let's calculate actual savings for a typical AI application:

Beyond Cost Savings: Why TOON is Better for Configs

1. Comments Support

Unlike JSON, TOON supports comments. This is crucial for configuration files where you need to document settings:

# Production database settings
[database]
host = "db.example.com"  # Main database
port = 5432
pool_size = 20  # Increase for high traffic

2. Native Date/Time Support

TOON has first-class date and time types, unlike JSON which requires string encoding:

created_at = 2026-01-17T10:30:00Z
expires = 2026-12-31

3. Cleaner Array of Objects

TOON's [[array]] syntax is more readable than JSON's nested arrays:

{
  "servers": [
    {"name": "alpha", "ip": "10.0.0.1"},
    {"name": "beta", "ip": "10.0.0.2"}
  ]
}

[[servers]]
name = "alpha"
ip = "10.0.0.1"

[[servers]]
name = "beta"
ip = "10.0.0.2"

Where TOON is Already Standard

• Rust (Cargo.TOON): Package manifests, dependencies, build settings
• Python (pyproject.TOON): PEP 518 build system, tool configs
• Hugo: Static site generator configuration
• Deno: TypeScript runtime configuration
• Netlify: Deployment and redirect configuration
• InfluxDB: Time-series database configuration

Best Practices for LLM Token Optimization

1. Use TOON for system prompts: Structure your prompts in TOON format
2. Convert API configs: Replace JSON configs sent to AI with TOON
3. Keep keys short: TOON keys aren't quoted, so short keys save more
4. Use tables wisely: [section] headers group related settings efficiently
5. Leverage arrays: [[table]] syntax is cleaner than JSON arrays of objects

Try It Now

Ready to start saving on LLM costs? Head to our JSON to TOON Converter and transform your configurations. It's free, runs entirely in your browser, and could save you hundreds of dollars per year in AI API costs.