• DATA
  • SECURITY
  • DEBUG
  • HUMAN

How to decode JWT claims with your AI client

Connect this MCP to your AI client once. After that, you can just paste any token and ask for the data inside.

Ask AI about this page

Short answer

How can I decode a JWT using my AI?

Paste the raw token into your chat and ask your AI to decode it. The AI uses the decode_jwt_token tool to turn the encoded string into a structured JSON object. You'll get a clear breakdown of the payload, headers, and expiration times.

The results you get

What you get from decoding

The AI handles the heavy lifting of parsing the string so you can focus on the data.

DATA

Readable JSON payloads

The AI extracts the claims. You get a clean object containing user IDs, roles, and permissions.

SECURITY

Expiration checks

Your agent can instantly pull the expiration claim. This tells you exactly when a token becomes invalid.

DEBUG

Header inspection

The tool pulls the algorithm and type from the header. This helps you verify how the token was signed.

HUMAN

Manual validation

The AI shows you the data, but you must decide if the claims match your application logic. It won't change the token itself.

The workflow

What your AI does when a token arrives.

The AI treats the raw string as input for a specific decoding operation.

  1. Receive token

    You paste a long, encoded JWT string into the chat window.

    decode_jwt_token

  2. Parse structure

    The AI runs the tool to split the token into its three constituent parts.

    decode_jwt_token

  3. Extract claims

    The tool converts the Base64Url encoded segments into a readable JSON format.

    decode_jwt_token

  4. Summarize data

    Your agent presents the key-value pairs, such as sub, iat, and iss, in plain text.

    decode_jwt_token

Try it

Copy these to start.

Use these prompts to get immediate results from your agent.

Starting points

Replace the bracketed text with your actual token or specific claim requirements.

JWT Decoder Connector

You're all set. Choose your MCP client and follow the setup instructions.

Connector linkhttps://edge.vinkius.com/vk_preview_JtisWyM2L8SwCbAosdXvoaNUkIeJdtsNTEISeftK/mcp

Claude Desktop

Follow the steps below to connect in seconds.

  1. 1In Claude Desktop, open Settings → Connectors.
  2. 2Click “Add custom connector” and paste the connector link above as the remote MCP server URL.
  3. 3Click Add and start a new chat — JWT Decoder capabilities are ready to use.
Configuration · claude_desktop_config.jsonCopy
{
  "mcpServers": {
    "jwt-base64-decoder-mcp": {
      "url": "https://edge.vinkius.com/vk_preview_JtisWyM2L8SwCbAosdXvoaNUkIeJdtsNTEISeftK/mcp"
    }
  }
}
Copy into chat04

  • Decode this JWT and show me the payload: [paste token here]

  • What is the expiration time in this token? [paste token here]

  • Check the issuer and subject claims for this token: [paste token here]

  • Decode this token and tell me if the 'admin' claim is set to true: [paste token here]

  • Claude
  • ChatGPT
  • Cursor
  • VS Code
  • Windsurf
  • Claude Code
  • JetBrains
  • Cline

Start here

Connect JWT & Base64 Decoder once, then ask.

One click connects this MCP to your client. Your credentials stay encrypted and the setup is handled on our end.

Connect JWT & Base64 Decoder to your AI

FAQ

How this task behaves

  • 01

    Can the AI modify the JWT claims?

    No. The tool only decodes existing data. It cannot edit, sign, or create new tokens.

  • 02

    Does this tool verify the digital signature?

    No. This tool decodes the Base64 content so you can read it, but it does not validate the cryptographic signature against a secret key.

  • 03

    Can I decode standard Base64 strings too?

    Yes, the MCP includes tools to handle standard Base64 encoding as well.

  • 04

    Will my tokens be stored by Vinkius?

    No. Vinkius hosts the connection, but we do not store your data or the tokens you process.

  • 05

    Can the AI use this to bypass authentication?

    No. Decoding a token only reveals what is inside it; it does not grant any permissions or bypass security checks.

  • More questions about JWT & Base64 Decoder? The Connector page answers them. See everything the JWT & Base64 Decoder Connector can do

Connect JWT Decoder to Claude, Cursor, ChatGPT & more