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clearjson
Privacy-first browser JSON viewer. Zero tracking. Fully local. Plus an MCP server for AI agents.
ClearJSON is a Chrome extension that automatically detects and formats JSON responses in your browser. Built in response to the JSON Formatter controversy — we will never inject ads, track you, or sell your data.
For AI agents (Claude Code, etc.): npx -y clearjson-mcp
{
"mcpServers": {
"clearjson": {
"command": "npx",
"args": ["-y", "clearjson-mcp"]
}
}
}
10 tools — format, validate, search, JSONPath query, deep diff, convert (CSV/TSV/YAML/TypeScript), plus license management. The only large-file-safe JSON MCP server. Available on npm and mcp.so. See AGENT_FIRST.md for the full rationale.
[ collapse, ] expand, D theme, R raw, Enter search nav)chrome://extensions/clearjson/
├── manifest.json # Chrome Extension manifest (MV3)
├── server/ # License server (Cloudflare Worker + D1)
│ ├── src/index.js # API: verify/generate/webhook/admin
│ ├── schema.sql # D1 database schema
│ └── wrangler.toml # Worker config
├── clearjson-mcp/ # MCP server (npm: clearjson-mcp)
│ ├── package.json
│ ├── src/
│ │ ├── index.js # MCP entry point (stdio transport)
│ │ ├── core/ # Core logic (parser, exporter, license)
│ │ └── tools/ # 7 JSON tools + 3 license tools
│ ├── tests/ # 49 MCP unit tests
│ └── README.md
├── src/
│ ├── content/
│ │ ├── content.js # Content script (JSON detection + viewer injection)
│ │ └── content.css # Base styles + CSS variable theming
│ ├── viewer/
│ │ ├── viewer.html # Standalone viewer page
│ │ └── viewer.js # Viewer logic
│ ├── popup/
│ │ ├── popup.html # Extension toolbar popup
│ │ ├── popup.js
│ │ └── popup.css
│ └── utils/
│ ├── parser.js # JSON detection + parsing
│ ├── tokenizer.js # Syntax highlighting tokenizer
│ ├── themes.js # 30 theme definitions
│ ├── license.js # Pro license system
│ ├── export.js # CSV/TSV/YAML/TypeScript export
│ ├── stream-parser.js # Web Worker streaming parser
│ ├── virtual-tree.js # Virtual scrolling tree view
│ └── tree.js # Standard tree view renderer
├── tests/ # 136 unit tests (Node built-in runner)
│ ├── helpers/setup.js
│ ├── test-parser.js
│ ├── test-tokenizer.js
│ ├── test-jwt.js
│ ├── test-license.js
│ └── test-export.js
├── test-data/ # Test data + automation scripts
│ ├── complex-api-response.json
│ ├── jwt-test.json
│ ├── users-array.json
│ ├── large-array.json # 2.2 MB for Pro gate testing
│ ├── server.js # Local test server (port 8765)
│ ├── run-checklist.js # 130-item static analysis
│ ├── browser-test.js # 21-item browser automation
│ └── TEST-CHECKLIST.md # 43-item manual checklist
├── icons/
│ ├── icon.svg
│ ├── icon16.png
│ ├── icon48.png
│ └── icon128.png
└── README.md
# For development, load the extension unpacked:
# 1. chrome://extensions/ → Developer mode ON
# 2. Load unpacked → select the project root
# 3. Edit files and click refresh on the extension card
# Run unit tests (zero dependencies, Node 18+):
npm test # 136 tests (Chrome extension)
cd clearjson-mcp && npm test # 49 tests (MCP server)
# Run static analysis checklist (130 checks):
node test-data/run-checklist.js
# Run browser automation tests (requires puppeteer):
node test-data/browser-test.js
# Start local test server (Pro auto-enabled on localhost:8765):
node test-data/server.js
All features implemented. Pro available via Creem ($29 lifetime). 136 unit tests passing. MCP server v1.1.0 published to npm.
See STATUS.md for full project state, architecture decisions, and release checklist.
ClearJSON processes everything locally. We promise:
Our permissions are minimal:
storage — save your theme preferenceactiveTab — format JSON in the current tabAfter the original JSON Formatter (2M+ users, 10 years open source) was sold and started injecting ads and tracking users, developers needed a trustworthy alternative. ClearJSON is built to be that alternative with a sustainable Pro model that respects users instead of exploiting them.
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