JWT Decoder MCP Server

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Decode and inspect JSON Web Tokens (JWT) without signature verification. Extract header, payload, claims, and expiration status. Supports JWS (signed) tokens. Pure computation — no external calls, no secrets needed.

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1 tool

Agent guide included

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AI Skill
SKILL.md

Domain knowledge for JWT Decoder — workflow patterns, data models, and gotchas for your AI agent.

JWT Decoder

Decode JSON Web Tokens to inspect their contents without needing the signing secret. Useful for debugging auth flows, checking token expiration, and understanding token claims.

Capabilities

Decode JWT: Split a token into header, payload, and signature. Parse all standard claims (iss, sub, aud, exp, nbf, iat, jti).
Expiration check: Determine if a token is expired, when it expires, and how much time remains.
Header inspection: View algorithm, token type, and key ID (kid) from the JOSE header.
Claim analysis: List all claims with human-readable labels for registered claim names.

Gotchas

No signature verification: This tool decodes tokens but does NOT verify signatures. It cannot tell you if a token is authentic — only what it contains.
JWE (encrypted tokens): Not supported. Only JWS (signed) tokens with base64url-encoded payloads.
Nested JWTs: If the payload contains another JWT, it is returned as a string — not recursively decoded.

Tools in this Server (1)

Jwt Decoder Decode

Decode a JSON Web Token (JWT) to inspect its header and payload. Shows all claims, checks expiration status, and identifies the signing algorithm. Doe...

Frequently Asked Questions

What is the JWT Decoder MCP server?

How do I connect JWT Decoder to my AI agent?

Add the MCPBundles server URL to your MCP client configuration (Claude Desktop, Cursor, VS Code, etc.). The URL format is: https://mcp.mcpbundles.com/bundle/jwt-decoder. Authentication is handled automatically.

How many tools does JWT Decoder provide?

JWT Decoder provides 1 tool that can be called by AI agents, along with a SKILL.md that gives your AI agent domain knowledge about when and how to use them.

What authentication does JWT Decoder require?

JWT Decoder uses open data APIs — no authentication required.

Setup Instructions

Connect JWT Decoder to any MCP client in minutes

MCP URL

https://mcp.mcpbundles.com/bundle/jwt-decoder

Claude.ai Cursor VS Code VS Code Insiders Goose LM Studio Cherry Studio ChatGPT

One-click install:

Install on Claude.ai Install for organization (admins)

The link prefills the Add custom connector dialog — you still review the values and click Add, then Connect to complete OAuth.

Or add manually

Open claude.ai → Settings → Connectors.
Click the + button and choose Add custom connector.
Set Name to JWT Decoder and paste the MCP URL into Remote MCP server URL.
Click Add. JWT Decoder will appear under Not connected — select it and click Connect to complete OAuth.