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TOON

Token-Oriented Object Notation — a compact data format designed for LLM applications. Practical guides and tools at jsonparser.ai. Practical guides and tools at jsonparser.ai.

Apr 17, 2026·8 min read

What is TOON Format? A Developer's Introduction

TOON (Token-Oriented Object Notation) is a compact data serialization format built for LLM applications. Here's what it is, why it was created, and when to reach for it.

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Apr 17, 2026·8 min read

TOON vs JSON — Which Should You Use?

JSON is universal. TOON is token-efficient. Both represent structured data — but for very different purposes. A practical comparison with real examples and a clear decision guide.

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Apr 17, 2026·9 min read

TOON vs JSON vs CSV — Choosing the Right Format

Three formats, three different jobs. JSON handles nested data, CSV dominates flat tables, and TOON bridges both while optimizing for LLM token budgets. Here's how to decide.

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Apr 17, 2026·9 min read

TOON Syntax Guide — From Scalars to Tabular Data

A complete reference for TOON syntax: scalars, objects, arrays, and the tabular notation that makes TOON uniquely efficient for structured datasets. Includes encode/decode examples.

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Apr 17, 2026·10 min read

Using TOON with LLMs — Cut Token Costs Without Losing Structure

Every token you send to an LLM API costs money. TOON can cut your structured data token count significantly. Here's how to use it in practice with the OpenAI and Anthropic APIs.

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Apr 17, 2026·9 min read

TOON Format Examples — Real-World Data Patterns

Documentation examples use toy data. This shows TOON with the data shapes you actually work with: product catalogs, audit logs, API metrics, financial transactions, and mixed documents.

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Apr 17, 2026·9 min read

TOON vs YAML — Two Compact Formats, Very Different Jobs

Both look cleaner than JSON, but YAML is optimised for human editing and TOON for machine processing. Here's where each one wins — and why YAML is actually worse than JSON for LLM token efficiency.

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Apr 17, 2026·10 min read

TOON in Node.js — From File I/O to LLM Pipelines

The practical side of TOON: reading and writing .toon files, building a request body parser, validating at system boundaries, and wiring TOON into a database-to-LLM pipeline.

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