JSON Editor

Edit, validate, compare, query and convert — all in one tool.

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{{ diff.added.length }} {{ __t('compare_added') }} {{ diff.removed.length }} {{ __t('compare_removed') }} {{ diff.modified.length }} {{ __t('compare_modified') }} {{ __t('compare_identical') }}
+ {{ p.path }} : {{ p.value }}
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~ {{ p.path }} : {{ p.from }} → {{ p.to }}
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{{ __t('query_input_label') }} (JSON)
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{{ __t('query_help_heading') }}: {{ __t('query_help_jsonpath') }} — JSONPath Docs {{ __t('query_help_jmespath') }} — JMESPath Spec

What is the CalcSI JSON Editor?

The CalcSI JSON Editor is a free online tool for editing, validating, comparing, querying and converting JSON data. Switch freely between three views — tree, text and table — and use advanced features like JSON repair, schema validation, diff comparison, JSONPath/JMESPath queries and conversion to YAML, CSV, XML or TypeScript interfaces.

All processing happens entirely in your browser — your data never leaves your device. Ideal for developers, API testers, DevOps engineers, and anyone working with JSON.

Three editor views

  • Tree view — Click to edit, drag-and-drop to reorder, keyboard shortcuts to add or remove nodes.
  • Text view — Full code editor with syntax highlighting, line numbers and inline error markers.
  • Table view — Display arrays of objects as a table, columns = keys. Perfect for API responses with records.

Feature set

  • Repair — Auto-fix trailing commas, unquoted keys, single quotes and comments.
  • Sort — Recursively order keys alphabetically for deterministic diffs and improved readability.
  • JSON Schema validation — Validate your data against a custom schema with types, required fields, min/max, patterns and more.
  • Compare (diff) — Two JSONs side-by-side with a clear list of added, removed and modified paths.
  • Query — JSONPath and JMESPath supported. Extract exactly the data you need with expressive paths.
  • Convert — Switch between JSON, YAML, CSV, XML and generate TypeScript interfaces from your data.
  • Import & export — Upload a file, load from URL, download as .json, copy to clipboard.
  • 100% local — All operations run in your browser; no data is uploaded or logged.

Common use cases

  • Inspect, filter and export API responses to other formats
  • Edit and validate configuration files (package.json, tsconfig, OpenAPI)
  • Data migration: convert JSON from one application to YAML/CSV/XML for another
  • Hunt bugs by diffing two snapshots (before / after a failure)

Is this tool secure?

Yes. All processing — parsing, validating, comparing, converting, querying — runs entirely in your browser. There is no server round-trip and no logging. You can inspect the source code at any time using your browser's developer tools. Even sensitive data like tokens or PII never leaves your device.