Convert JSON to TOON.
Feed your LLM less, get more.
TOON (Token-Oriented Object Notation) strips JSON's redundant syntax so your AI models receive the same data in 30–60% fewer tokens — cutting API costs and speeding up every call.
Everything you need to ship lean LLM prompts
JSONtoTOON is purpose-built for AI developers who care about token efficiency, data privacy, and a friction-free workflow.
Real-time Conversion
Results appear as you type with a 300 ms debounce — no clicking "submit".
100% Private
All processing happens in your browser. No server, no tracking, no cookies.
Token Analytics
Exact token counts and API cost estimates powered by the GPT o200k_base tokenizer.
Mobile-Friendly
Fully responsive — works on phone, tablet, and desktop.
Works with Any LLM
GPT-4, Claude, Llama, Mistral, Gemini — TOON is tokenizer-agnostic.
File Import & Export
Drag-and-drop, upload, or paste. Download results as .toon or .json.
Bidirectional
JSON → TOON → JSON with zero data loss. Perfect for validation.
Configurable
Choose delimiter (comma or tab), pretty-print, auto-convert, and font size.
Sample Templates
Pre-loaded examples to test conversion instantly
Quick Access
JSON to TOON Converter
Paste JSON, click Convert — save 40–60% tokens instantly
JSON Input
TOON Output
TOON output will appear here...Token Analytics
Select a template or paste JSON, then click Convert to see token savings and cost estimates.
How to use JSONtoTOON
Five steps to your first token-optimised prompt.
- Step 1
Paste your JSON or upload a file
Copy JSON and paste it into the input field, or drag and drop a .json file. Files up to 50 MB are supported.
- Step 2
Click Convert or enable auto-convert
Click the Convert button or turn on auto-convert in Settings for real-time output as you type (300 ms debounce).
- Step 3
See your token savings
The analytics panel shows exact token counts and estimated API cost savings immediately after conversion.
- Step 4
Copy or download the TOON output
Click Copy to grab the TOON text, or Download to save a .toon file. Use it directly in your LLM prompt.
- Step 5
Convert back to JSON anytime
Paste TOON into the right pane and click Reverse. The conversion is lossless — you get back identical JSON.
When does TOON format help most?
Any time you pass structured data to an LLM, TOON reduces your token bill.
Real example — API response
{
"users": [
{
"id": 1,
"name": "Alice",
"email": "alice@example.com",
"active": true
},
{
"id": 2,
"name": "Bob",
"email": "bob@example.com",
"active": true
}
]
}users[2]{id,name,email,active}:
1,Alice,alice@example.com,true
2,Bob,bob@example.com,true✓ Same data structure, lossless round-trip.
LLM Prompt Engineering
Most commonPass structured data — user records, API responses, config — to GPT-4, Claude, or Llama using 30–60% fewer tokens. Lower latency, lower cost, same accuracy.
API Development
Shrink JSON payloads before they go into AI-augmented pipelines, cutting bandwidth and reducing token overhead in downstream calls.
Data Pipelines & ETL
Convert large JSON exports to TOON before feeding them into analysis steps or fine-tuning datasets — keeps file sizes manageable.
Log & Event Analysis
Structured logs become dramatically smaller in TOON, especially when arrays of identical event objects are compressed into tabular rows.
Config & Settings Files
Store application configs in TOON for compact, human-readable version control. Easy to diff, easy to send to an LLM for explanation or editing.
Progressive Web Apps
Use TOON in localStorage or IndexedDB to reduce cached data size — faster load times on slow networks.
Frequently asked questions
Everything you need to know about JSON to TOON conversion.
Learn more about TOON
Deep-dive guides on TOON format, token optimisation, and LLM best practices.