JSON to TOON Converter Online – Private & Bidirectional
Switch direction to decode TOON back to JSON. Tune indentation, tabular delimiters, and optional key folding for smaller prompts.
When JSON ⇄ TOON helps
Convert JSON to TOON (Token-Oriented Object Notation) and back in your browser. TOON uses compact headers and rows for uniform lists—useful for LLM prompts—while round-tripping the JSON data model.
Encoding and decoding run entirely in your browser using the reference @toon-format/toon implementation. Your payloads are not uploaded.
Frequently asked questions
What is TOON?
TOON (Token-Oriented Object Notation) is a line-oriented format for the same data model as JSON. Uniform arrays of objects become a header plus delimiter-separated rows, which often reduces tokens in LLM contexts compared to verbose JSON.
Will TOON → JSON → TOON match exactly?
The data round-trips: values and structure match JSON semantics. Whitespace and key folding may differ from hand-written TOON. If you encoded with Safe key folding, enable “Expand dotted keys” when decoding for nested JSON objects.
Why does my array still look like a list with hyphens?
Tabular compression applies only when every element is an object, all share the same keys, and every field value is a primitive (string, number, boolean, or null). Mixed arrays or nested objects fall back to expanded list encoding per the TOON spec.
Is my data sent to a server?
No. Parsing, encoding, and decoding run locally in your browser.
Which TOON version do you implement?
This page uses the open-source @toon-format/toon library aligned with the community TOON specification (see toonformat.dev). Edge cases follow the library and spec behavior.
Where can I read more about trade-offs vs JSON?
See the JSON Work article on TOON vs JSON for LLM pipelines: token savings, nesting, and when to stay on JSON.