MCP JSON Sanitizer

Remote MCP server on Cloudflare Workers that repairs malformed JSON strings into valid JSON for agent workflows.

What It Does

json_sanitizer accepts a string that is supposed to be JSON but may have common LLM formatting issues. The Worker applies deterministic cleanup steps and returns valid JSON when recovery succeeds.

Handled fixes include:

• code fence removal

• smart quote normalization

• extraction of the JSON body from surrounding prose

• quoting bare object keys

• conversion of single-quoted strings

• trailing comma removal

• closing missing } and ]

Related MCP server: json-sanity

Tool

json_sanitizer

Input:

• input: malformed JSON-like string

• pretty?: pretty-print output JSON, defaults to true

Output:

• repaired JSON text

• structured metadata with applied fixes and parsed JSON value

Transport

• MCP endpoint: https://<your-worker>.workers.dev/mcp

• Well-known manifest: https://<your-worker>.workers.dev/.well-known/mcp/server.json

• Health check: https://<your-worker>.workers.dev/health

Monetization

Only actual tool execution requires payment:

• free: GET /mcp, tools/list, initialize, ping

• paid: tools/call for json_sanitizer

Payment settings:

• network: eip155:8453 (Base)

• asset: USDC

• price: 0.001

• payTo: 0x4505A361611DebB4928Db488ad7E345cD5821cD4

Deploy

1. Install dependencies with npm install.

2. Authenticate Wrangler with npx wrangler login.

3. Set the settlement signer privately with npx wrangler secret put EVM_PRIVATE_KEY.

4. Update PUBLIC_BASE_URL in wrangler.toml to your final Worker URL.

5. Deploy with npm run deploy.