jsonkit

Live site: https://viveknaskar.github.io/json-kit/

Free, open-source JSON tools that run entirely in your browser. No sign-up, no server uploads, your data never leaves your device.

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Screenshots

Essentials

Format & Validate	Minify JSON	Sort Keys

Repair JSON	Escape / Unescape

Convert

JSON to CSV	CSV to JSON	JSON to YAML

YAML to JSON	JSON to XML	XML to JSON

Analyze & Transform

JSON Merge	JSON Diff	Schema Validator

Flatten JSON	Unflatten JSON	JSON Query

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Features

• 100% client-side: all processing happens in the browser, no backend, no cloud
• No data uploads: JSON is parsed and transformed entirely in your browser tab
• Works offline: once loaded, every tool works without an internet connection
• No sign-up, no limits, no watermarks
• 24 tools covering formatting, conversion, diffing, querying, and more
• Dark / light mode toggle with OS preference detection and sound feedback

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How does it Work?

When you paste JSON into any tool, it never leaves your device. Here is exactly what happens:

1. Your input is read into memory inside the browser tab as a plain JavaScript string.
2. All parsing and transformation runs locally using pure JavaScript, no WebAssembly, no server calls.
3. The result is written back to the page as a string, still entirely in memory.
4. If you download, the browser generates a temporary local Blob URL, triggers the download, then immediately revokes it.
5. When you close the tab, everything is gone. No trace left anywhere.

No data is ever sent over the network. There is no backend, no database, and no cloud storage involved. You can turn off your WiFi after the page loads and every tool will still work.

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Tools

Essentials

Tool	Description
Format & Validate	Prettify JSON and detect parse errors with line and column info.
Minify JSON	Compress JSON by stripping all whitespace. Shows size reduction.
Sort Keys	Sort all object keys alphabetically, recursively through nested structures.
Repair JSON	Fix trailing commas, single quotes, unquoted keys, and inline comments.
Escape / Unescape	Escape a raw string for use inside a JSON value, or unescape it back.

Convert

Tool	Description
JSON to CSV	Convert a JSON array to CSV. Headers are sorted; nested values are serialised.
CSV to JSON	Parse CSV (including quoted fields and CRLF) into a typed JSON array.
JSON to YAML	Hand-rolled YAML serialiser, no external library required.
YAML to JSON	Hand-rolled YAML parser, handles sequences, mappings, and all scalar types.
JSON to XML	Convert JSON to structured XML wrapped in <root>. Arrays repeat the parent tag.
XML to JSON	Parse XML back to JSON. Repeated siblings become arrays; text is type-coerced.
JSON to TypeScript	Generate TypeScript interface definitions from any JSON object.
JSON to Markdown	Convert a JSON array to a Markdown table.

Analyze & Transform

Tool	Description
JSON Merge	Deep merge two JSON objects. Choose between replace or concat array strategy.
JSON Diff	Deep-compare two JSON objects and highlight added, removed, and changed keys.
Schema Validator	Validate JSON against a JSON Schema definition (type, required, pattern, enum, allOf, anyOf, oneOf, not, if/then/else, and more).
Flatten JSON	Flatten nested objects to dot-notation keys (a.b.c, arr[0]). Configurable separator.
Unflatten JSON	Restore dot-notation flat keys back to a nested structure.
JSON Query	Extract values using path expressions (users[0].name, items[*].id).
Base64 Encode/Decode	Encode text or JSON to Base64, or decode it back.
Remove Nulls	Strip null values, empty strings, and empty collections from JSON.
Pick / Omit Keys	Extract or remove specific dot-notation key paths from a JSON object.
Mock Generator	Generate realistic fake JSON data from a JSON Schema. Supports formats, enums, nested objects, and semantic field-name hints.
JWT Decoder	Decode JWT headers, payloads, and claims. Shows expiry status, time remaining, and human-readable timestamps for iat/exp/nbf.

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Contributing

See CONTRIBUTING.md for setup instructions, project structure, and how to add a new tool.

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License

MIT