{
  "markdown": "# JWT Decoder API\n\n[![MCP Server](https://img.shields.io/badge/MCP-server-blue)](https://jwt-decoder.api.klymax402.com/mcp)\n[![x402](https://img.shields.io/badge/payments-x402-6E56CF)](https://x402.org)\n[![License: MIT](https://img.shields.io/badge/license-MIT-green)](LICENSE)\n\nDecode and inspect JWT tokens without verification. Extracts header, payload, claims, expiry, and signature algorithm. Pay-per-call via [x402](https://x402.org) (USDC on Base L2) -- no API key, no signup, no rate-limit wall.\n\nPart of the [klymax402](https://klymax402.com) marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.\n\n## Quickstart -- MCP\n\nAdd to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):\n\n```json\n{\n  \"mcpServers\": {\n    \"jwt-decoder\": {\n      \"url\": \"https://jwt-decoder.api.klymax402.com/mcp\"\n    }\n  }\n}\n```\n\n## Quickstart -- HTTP (x402)\n\n```bash\ncurl -X POST \"https://jwt-decoder.api.klymax402.com/api/decode\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"token\":\"...\"}'\n# -> 402 Payment Required, with an x402 payment challenge in the response body\n```\n\nAny x402-aware client ([`@x402/fetch`](https://www.npmjs.com/package/@x402/fetch), [`x402-agent-tools`](https://www.npmjs.com/package/x402-agent-tools), ATXP) handles the 402 -> sign -> retry cycle automatically.\n\n## Tools\n\n| Tool | Method | Path | Price | Description |\n|---|---|---|---|---|\n| `security_decode_jwt` | POST | `/api/decode` | $0.003 | Decode a JWT token without signature verification |\n\n### `security_decode_jwt`\n\nUse this when you need to decode and inspect a JWT token without verifying its signature. Returns the full header, payload, and expiration status.\n\n**Parameters**\n\n| Name | Type | Required | Description |\n|---|---|---|---|\n| `token` | string | yes | The JWT token to decode (format: header.payload.signature) |\n\nExample response:\n\n```json\n{\"header\":{\"alg\":\"RS256\",\"typ\":\"JWT\"},\"payload\":{\"sub\":\"user123\",\"exp\":1720000000},\"issuedAt\":\"2025-01-01T00:00:00Z\",\"expiresAt\":\"2025-07-03T00:00:00Z\",\"isExpired\":false}\n```\n\n**When to use**: debugging authentication issues, inspecting token claims before API calls, or verifying token expiry. Use this BEFORE making authenticated requests to check if a token needs refreshing.\n\n**Not for**: hashing data (use `crypto_generate_hash`), base64 encoding/decoding (use `utility_encode_base64`), password analysis (use `security_check_password`).\n\n## Example agent prompts\n\n- \"Decode and inspect a JWT token without verifying its signature\"\n\n## Payment\n\n- Protocol: [x402](https://x402.org) -- HTTP-native pay-per-call, no signup, no API key\n- Network: Base L2 (`eip155:8453`)\n- Asset: USDC\n- Facilitator: Coinbase CDP (primary), PayAI (fallback)\n- Also reachable via [ATXP](https://atxp.ai) (OAuth-wrapped x402, RFC 9728 protected-resource metadata)\n\n## Part of klymax402\n\n100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.\n\n- Catalog: https://klymax402.com/llms.txt\n- Full API reference: https://klymax402.com/llms-full.txt\n- Live stats: https://klymax402.com/stats\n\n## License\n\nMIT\n",
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  "sha": "e27673cec5f8d19d987a31c90fbd2b4cd07ea5c29a70b91169e643cf76c162d3",
  "repo_slug": "br0ski777/jwt-decoder-x402",
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  "api": "https://agentalog.com/api/listings/mcp_io_github_br0ski777_jwt_decoder_50323901/readme"
}