JSON Toolbox

Local-first JSON/CSV/YAML/XML conversion for developers. No server, no telemetry, deterministic output.

Input → Transform → Output
  ↑        ↑         ↓
 CSV    Validate   TypeScript
 XML    Format     Schema
 YAML   Repair     Tree View

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Quick Start

Use it in 10 seconds:

1. Open mackan.eu/tools/json
2. Paste your data
3. Click convert

No signup. No installation. Works offline after first load.

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Examples

CSV → JSON

Input:

name,role,active
Alice,admin,true
Bob,user,false

Output:

[
  {"name": "Alice", "role": "admin", "active": true},
  {"name": "Bob", "role": "user", "active": false}
]

JSON → TypeScript

Input:

{"id": 1, "name": "Product", "price": 29.99, "tags": ["sale"]}

Output:

interface Root {
  id: number;
  name: string;
  price: number;
  tags: string[];
}

Repair Broken JSON

Input:

{name: 'Alice', active: true,}  // single quotes + trailing comma

Output:

{"name": "Alice", "active": true}

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Capabilities

Operation	Input	Output	Notes
CSV	CSV, TSV	JSON	Auto-detect delimiter, transpose
	JSON	CSV	Array-of-objects export
XML	XML	JSON	Preserves attributes
	JSON	XML	Configurable output
YAML	YAML	JSON	YAML 1.2 compliant
	JSON	YAML	Flow/block style
Format	JSON	JSON	Beautify, minify, sort keys
Validate	JSON	Report	Syntax + schema validation
Repair	Broken JSON	Valid JSON	Trailing commas, quotes, comments
Diff	2× JSON	Diff	Visual comparison
Query	JSON	Subset	JSONPath expressions
Schema	JSON	JSON Schema	Draft-07
Transform	JSON	TS/Go/Python	Interfaces, structs, dataclasses
Utilities	String	String	Base64, URL encode, escape
Tree	JSON	Tree view	Interactive navigation

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Why Local Execution?

Concern	Server-based	JSON Toolbox
Data privacy	Sent to third party	Never leaves browser
PII/PHI handling	Compliance risk	No compliance burden
Offline	Requires internet	Works offline
Speed	Network latency	Instant
Determinism	Server may change	Same input = same output
Enterprise	May violate policy	IT-approved friendly

When to use JSON Toolbox:

• Converting production data exports with PII
• Working with API keys or credentials
• Processing proprietary business data
• Air-gapped or regulated environments
• Needing reproducible, auditable output

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Keyboard Shortcuts

Press ? to view all shortcuts.

Shortcut	Action
?	Show shortcuts
Ctrl+Enter	Run operation
Ctrl+1-9	Switch tabs
Ctrl+Shift+C	Copy output

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Offline & Air-Gapped

JSON Toolbox works fully offline after initial page load.

For air-gapped environments:

1. Load page once with internet
2. All resources cached locally
3. Disconnect — tool continues working

Disable analytics entirely:

<script>window.ANALYTICS_DISABLED = true;</script>

Or download this repo and self-host.

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FAQ

Is my data sent anywhere?

No. All processing happens in your browser. User data never leaves your machine.

Can I use this with PII/PHI/sensitive data?

Yes. JSON Toolbox is designed for regulated workloads. Data stays local, no compliance burden.

What about analytics/telemetry?

Telemetry: None. No user tracking, no identifiers, no fingerprinting.

Analytics: Optional aggregate usage stats (which tabs are used). Cookieless, self-hosted, respects DNT. Disable with ANALYTICS_DISABLED = true.

Does it work offline?

Yes. After first load, all features work without internet. No external dependencies at runtime.

What dependencies does it use?

Self-hosted only (no CDN):

• PapaParse — CSV parsing
• js-yaml — YAML parsing
• jsonrepair — JSON fixing
• Lucide — Icons

No frameworks, no build systems, no external services.

Can I self-host this?

Yes. Clone this repo, serve statically. Set ANALYTICS_DISABLED = true for full air-gap.

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Philosophy

JSON Toolbox follows the Deterministic Developer Utility pattern:

1. Local execution — No network calls during operation
2. Deterministic output — Same input → same output, always
3. Zero onboarding — Paste, click, done
4. No side effects — Nothing installed without consent
5. Keyboard-first — Full operation via shortcuts

This is a tool, not a service.

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Policies

Privacy

• Zero telemetry (no user tracking)
• Optional aggregate analytics (cookieless, self-hosted, opt-out)
• No cookies
• User data never transmitted

Dependencies

• Allowed: Local-only capability libraries
• Disallowed: Frameworks, CDNs, external services

Accessibility

• WCAG AA contrast (≥4.5:1)
• Full keyboard navigation
• Screen reader compatible

See SECURITY.md for full security model.

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Suite

JSON Toolbox is part of the mackan.eu developer utility suite — a collection of deterministic, privacy-first tools:

Tool	Purpose	Status
JSON Toolbox	Data conversion & manipulation	v1.0.0
Password Generator	Cryptographic passwords	Available
Image Converter	Local format conversion	Available
Coordinate Converter	GPS transformation	Available

Suite philosophy: Local execution, zero telemetry, deterministic output.

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Project Structure

├── index.php          Main page
├── lang.php           i18n strings (sv/en)
├── script.js          Core logic, shortcuts
├── style.css          Design system
├── modules/           13 capability modules
│   ├── csv.js, xml.js, yaml.js, css.js
│   ├── format.js, validate.js, fix.js
│   ├── diff.js, query.js, schema.js
│   └── transform.js, utilities.js, tree.js
├── vendor/            Self-hosted libraries
├── docs/              QA reports, design docs
└── SECURITY.md        Security policy

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Contributing

See CONTRIBUTING.md for guidelines.

TL;DR: PRs welcome. No new dependencies. No telemetry. Preserve local-only execution.

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License

MIT

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Version: 1.0.0
URL: mackan.eu/tools/json
Source: github.com/retea-se/json