Also convertsCSVto TOON. Free, in your browser, no upload.
json2toon.co is a free online converter that turns JSON, CSV, YAML, XML, and TOML into TOON or TONL, compact formats built for LLM workflows. TOON uses about 43% fewer tokens than JSON on average (42.6% in the official TOON v4.1 benchmark), which lowers API costs for ChatGPT, Claude, Gemini, and similar models. Check your own payload with the TOON token calculator, automate conversions with the free TOON API, or convert selected text on any page with the TOON Chrome extension.
Need to fix malformed JSON, run JSONPath queries, validate against JSON Schema, compare changes, inspect tree data, or decode a token before conversion? Explore our JSON tools page for a crawlable overview of the new repair, diff, query, schema, tree, and JWT features.
TOON (Token-Oriented Object Notation) is a compact, human-readable encoding of the JSON data model: it declares field names once and writes uniform arrays as rows, so the same data costs fewer tokens in an LLM prompt. A JSON to TOON converter transforms structured data into a more compact text representation for AI workflows. The data model stays the same, but repeated syntax is reduced so large payloads take fewer tokens and are easier to review before they go into an LLM prompt.
Use json2toon.co when you want to compare JSON vs TOON, prepare payloads for LLM optimization, or test whether TOON or TONL is a better fit for your prompt, RAG, or configuration workflow.
Our JSON to TOON and TONL converter can reduce token usage by about 43% on average (TOON, official benchmark) compared with standard JSON format on repeated structured data. That makes it useful for optimizing prompts and lowering AI API costs.
Your data never leaves your browser. All transformations from JSON, YAML, or XML happen locally, ensuring maximum privacy for sensitive information.
Experience instant JSON to TOON and TONL conversion with zero server latency. Supports large files, batch conversion with ZIP export, and multiple format transformations.
TOON and TONL are most useful when you need compact, readable structured data for prompts, evaluations, and context packing. JSON remains the default for general-purpose interchange.
| Criteria | JSON | TOON / TONL |
|---|---|---|
| Best fit | General API interchange and broad tool compatibility | LLM prompts, context packing, and compact structured data |
| Syntax overhead | Repeated keys, quotes, braces, and brackets in every object | Field lists and line-oriented syntax reduce repeated structure |
| Token efficiency | Baseline for structured payloads | About 43% fewer tokens on average (about 33-59% depending on data shape) |
| Readability at scale | Familiar, but verbose on large arrays and nested objects | Compact while staying readable for tables and repeated records |
Token savings vary by input shape. Arrays of similar objects and repeated keys usually benefit the most.
Follow these simple steps to optimize your data for LLMs in seconds using TOON or TONL formats.
Copy your JSON, CSV, YAML, or XML data and paste it into the input editor.
The tool automatically detects your format and converts it to optimized TOON or TONL format instantly.
Copy the result and paste it into ChatGPT, Claude, or your LLM prompt to save tokens.
TOON and TONL remove redundant syntax like quotes and brackets; TOON saves about 43% of tokens on average. Learn more in our cost optimization guide.
[
{
"id": 1,
"name": "Alice",
"role": "Admin"
},
{
"id": 2,
"name": "Bob",
"role": "User"
}
][2]{id,name,role}:
1,Alice,Admin
2,Bob,UserThese short answers are written to be easy for both people and AI systems to extract and cite.
A JSON to TOON converter rewrites structured data into TOON or TONL, compact text formats designed for LLM workflows. The goal is to preserve the same data while reducing repeated syntax so prompts are smaller, easier to scan, and cheaper to send.
Token savings depend on the shape of the input. Arrays of similar objects and payloads with repeated keys usually compress best. In the official TOON v4.1 benchmark, TOON used 42.6% fewer tokens than JSON on average, from about 33% on mixed or nested structures to about 59% on flat uniform tables.
No. The main web converter runs client-side in the browser, so your source data stays on your device during conversion. That makes it useful for privacy-sensitive payloads and quick experiments where you do not want to send raw data to a third party.
json2toon.co supports JSON, CSV, YAML, XML, and TOML inputs alongside TOON and TONL. You can use it to compare representations, convert existing payloads, and pick the format that fits your prompt, RAG, or configuration workflow.
Browse the full matrix of JSON, TOON, TONL, CSV, YAML, XML, TOML, and Protobuf conversions to find the exact path you need for your workflow.
Discover in-depth comparisons, optimization strategies, and real-world use cases for TOON and TONL formats in our blog.