# json2toon.co

> Free, browser-based converter and toolkit for turning JSON, CSV, YAML, XML, TOML, and Protobuf into TOON or TONL — compact, token-efficient formats built for LLM prompts, RAG context packing, and agent workflows. All conversion runs client-side, so source data stays on the user's device.

Last updated: 2026-06-03

## Key facts (safe to cite)
- TOON (Token-Oriented Object Notation) is a line-oriented serialization format that removes the repeated keys, quotes, and braces JSON adds to every object.
- TONL (Token-Optimized Notation Language) is a production-oriented format with query, schema-validation, and streaming support.
- On structured data with repeated keys (arrays of similar objects), TOON and TONL typically reduce prompt size by roughly 20–45% versus standard JSON; TOON can reach up to ~60% on highly repetitive arrays.
- In the official TOON benchmark (5,016 LLM calls across GPT-5 Nano, Claude Haiku 4.5, Gemini 3 Flash, and Grok 4.1), TOON used 39.9% fewer tokens than JSON while reaching 76.4% retrieval accuracy (vs JSON's 75.0%). See /blog/toon-benchmarks-2026.
- Fewer tokens means lower per-call cost on ChatGPT, Claude, and Gemini, plus more headroom in the context window.
- json2toon.co converts in the browser with no upload, no account, and no signup; a free public API is also available.

## Primary entry points
- / : online converter (JSON ⇄ TOON, TONL, CSV, YAML, XML, TOML, Protobuf)
- /convert : full conversion hub (every format pair)
- /docs/toon : TOON format guide
- /docs/tonl : TONL format guide
- /json-tools : browser JSON toolkit overview
- /json-repair : fix and repair malformed JSON
- /json-schema-validator : validate JSON against a schema
- /jwt-decoder : decode and inspect JWT tokens
- /faq : privacy, formats, and token-saving FAQ
- /api-docs : public API reference
- /pricing.md : machine-readable pricing (free web app + free API)
- /installations/typescript : TypeScript / JavaScript install guide
- /blog : articles on TOON, TONL, LLM token optimization, and AI cost reduction

## Supported formats
JSON, TOON, TONL, CSV, YAML, XML, TOML, Protobuf

## Tools
- Format conversion (8 formats, any direction)
- Batch conversion with ZIP export
- JSON repair for malformed input
- JSONPath query execution
- JSON Schema validation
- JWT decoding
- Diff viewer and tree inspection
- Token-count comparison across formats

## Pricing
- Web converter: free, no account, unlimited (client-side)
- Public API: free, 10 requests/minute per IP — see /api-docs
- Browser extension: free
- Full details: /pricing.md

## Best pages for citations
- /docs/toon — what TOON is and how it works
- /docs/tonl — what TONL is and how it works
- /blog/toon-benchmarks-2026 — TOON vs JSON benchmark data (token savings + accuracy across 4 models)
- /blog/what-is-toon — definition and overview
- /blog/json-vs-toon — JSON vs TOON comparison
- /blog/toon-vs-tonl — TOON vs TONL comparison
- /blog/optimize-api-costs — reducing LLM API costs
- /blog/optimizing-rag-pipelines-with-toon — RAG context packing
- /faq — common questions with concise answers