How to use the TOON Validator
- Paste your TOON into the editor, or open a file.
- Validation runs automatically as you type.
- Fix any reported error using the line and column shown.
About TOON
TOON (Token-Oriented Object Notation) is a compact encoding of JSON designed for LLM prompts. It uses YAML-style nesting and CSV-style rows for uniform arrays, typically cutting token counts substantially compared with JSON.
Private by design
Developer data is often sensitive: API responses, tokens, customer records, internal configs. This TOON Validator processes everything locally in your browser tab. There is no server round-trip, no logging and no storage of your input.
Frequently asked questions
Is this TOON Validator free?
Yes. This TOON Validator is completely free to use with no sign-up, no limits and no ads inside the tool.
Is my data uploaded to a server?
No. The TOON Validator runs entirely in your browser using JavaScript. Nothing you paste is sent to DevT Pro or any other server.
What does the TOON Validator check?
It parses your input with a standards-compliant TOON parser and reports the first syntax error with its message.
Can I use the TOON Validator offline?
Yes. TOON Validator is also built into DevT Pro, a native app for Mac, Windows, iPad and Linux with 120+ developer tools that work fully offline. It is a $5.99 one-time purchase with no subscription.
