What Is TOON Format?
TOON is a compact representation intended for structured data in language-model prompts. Repeated keys in uniform object arrays can be listed once as table headers. It is a prompt format rather than a drop-in replacement for JSON API contracts.
How to Convert JSON to TOON
Paste valid JSON, adjust the converter settings and inspect the TOON output. Copy the result for your prompt. Use the reverse direction to check a round trip on representative examples before relying on it for a workflow.
When TOON Reduces LLM Prompt Tokens
Uniform rows with repeated property names are promising candidates for savings. Tiny objects, irregular nesting and verbose string values may gain little. The displayed token count is a character-based estimate, not a model tokenizer measurement or a billing guarantee.
JSON vs TOON Examples
An array of user records repeats fields such as id and name in JSON. A tabular representation can put those field names in a header and list one record per row. Compare both outputs for missing fields and delimiter-sensitive strings.
When Not to Use TOON
Keep JSON when an API requires it, when exact interoperability matters or when your model handles JSON more reliably. This converter implements a limited TOON-style representation; depth limits and field exclusions can change output. Always check the result on nested and irregular inputs.
Frequently asked questions
What is TOON format?
It is a compact structured-data representation for prompts that can reduce repeated keys in regular arrays.
How much can TOON reduce token usage?
Savings depend on data shape and the model tokenizer. The tool estimates tokens from character count; verify real token usage with your model’s tokenizer.
Does TOON preserve nested JSON structures?
Nested values are supported within this converter’s limits, but depth limits, exclusions and irregular structures require round-trip checks.
Which LLM workflows benefit from TOON?
Prompt workflows that include repeated structured records can benefit. Test accuracy as well as token count.
Is the conversion client-side?
Yes. Conversion runs in this tab.