JSON Repair and Formatter
Fix common JSON issues such as trailing commas, single quotes, broken escaping, and malformed structures. Then pretty-print, minify, sort keys, or escape JSON for string literals.
Open tool →Free JSON Tools Online
Repair malformed JSON, format and minify documents, compare diffs, run JSONPath queries, validate against JSON Schema, inspect tree structures, and decode JWTs in one browser-based workspace. These tools are designed to help you clean and inspect structured data before you send it to an API or convert it to TOON or TONL.
Included JSON tools
Six small utilities for cleaning and inspecting JSON before you convert it.
JSON Diff Viewer
Compare original and transformed JSON side by side so you can review changes before sharing, copying, or converting data to TOON or TONL.
Open Diff Viewer →JSONPath Query Tool
Run JSONPath expressions against nested payloads to extract values, filter arrays, and inspect the exact fields you need without writing one-off scripts.
Open JSONPath Query →JSON Schema Validator
Validate documents against JSON Schema Draft-07 in the browser with Ajv-powered error output and line-aware validation messages.
Open tool →JSON Tree Viewer
Inspect large or deeply nested payloads in a structured tree view when raw text becomes difficult to scan or debug.
Open Tree Viewer →JWT Decoder
Decode JWT header and payload claims locally, inspect expiry information, and review standard token fields without sending secrets to a server.
Open tool →A simple JSON workflow
- 1. Paste a JSON document or token you want to inspect.
- 2. Repair, query, validate, diff, or decode it in the browser.
- 3. Convert the cleaned payload to TOON or TONL when you want a smaller prompt footprint. Check the savings with the TOON token calculator.
When to use this page
- Use JSON Tools when you need repair, validation, querying, inspection, or token decoding.
- Use JSON Repair when the document is malformed and standard parsers fail immediately.
- Use JSON Schema Validator when you need contract validation for APIs or configs.
- Use JWT Decoder when you need to inspect claims without sending tokens off-device.
- Use the main converter when your goal is to transform JSON, CSV, YAML, XML, TOML, TOON, TONL, or Protobuf.
- Use the TOON API when you need JSON to TOON conversion from a script or backend.
- Use the TOON Chrome extension when you want to convert JSON you see on any web page.
- Use the TONL guide when you want advanced query and schema concepts tied to the TONL ecosystem.
JSON tools FAQ
Do these JSON tools upload my data?
No. The JSON tools on json2toon.co run in the browser, so your JSON documents and JWTs stay on your device while you inspect, repair, or validate them.
Can I use these JSON tools before converting data to TOON or TONL?
Yes. The tools are useful for cleaning malformed JSON, validating schemas, querying nested data, and reviewing diffs before you convert structured payloads for LLM workflows.
Which JSON tasks are covered on this page?
This page covers JSON repair, formatting, minification, key sorting, JSONPath queries, JSON Schema validation, tree inspection, document diffing, and JWT decoding.
Clean JSON first, optimize it second
Start with JSON repair, queries, schema validation, and JWT inspection, then move into TOON or TONL conversion when you want a more compact format for LLM workflows.