Back to Comparisons
JSON vs TOON
Traditional hierarchy vs Token-Oriented Object Notation.
TOON (Token-Oriented Object Notation) was born in the era of Generative AI. While JSON uses repetitive symbols ("{}", "[]", ":", ",") that consume valuable tokens, TOON uses indentation and headers to represent the same data model. For uniform lists (tabular data), it eliminates repeating keys for every object, which is where the real token savings happen.
Why choose TOON?
- 30-60% fewer tokens than JSON.
- Optimized for LLM context windows.
- Highly readable tabular data.
- Explicit size hints [N] reduce parsing errors.
Trade-offs
- Not yet a standard for general web APIs.
- Requires a translator for non-LLM usage.
- Less documentation than legacy formats.
Best Use Cases
1
Prompt Engineering context data.2
Saving costs on LLM API calls.3
Structured logging for AI analysis.Visual Comparison
Example Payload
Standard JSON
{
"users": [
{"id": 1, "name": "Alice", "role": "Admin"},
{"id": 2, "name": "Bob", "role": "User"}
],
"meta": { "total": 2 }
}* High symbol redundancy, repeatable keys.
TOON Format
Token Optimized
users[2]: {id, name, role}
1, Alice, Admin
2, Bob, User
meta:
total: 2Saves ~40% tokens in this example.
Structure
JSON maps to HashMaps. TOON maps to Objects.
Safety
JSON is simple data. TOON offers flexible editing.
Parsers
TOON parsers are available in all major languages.