How to Use the JWT & Base64 Decoder MCP in Claude Code

Q: How do I add the JWT & Base64 Decoder to Claude Code?

Run claude mcp add --transport http jwt-base64-decoder -- in your terminal. You can verify the installation by running claude mcp list to see the active tools.

Q: Can Claude Code decode encrypted JWTs using JWT & Base64 Decoder?

No. The decodejwttoken tool only parses standard, unencrypted JWS tokens. It splits the token into its three base64url-encoded parts and decodes them, but it cannot decrypt JWE tokens that require private keys.

Q: Why use the JWT & Base64 Decoder instead of native shell commands?

While you can use openssl or base64 commands, this MCP Server lets Claude Code decode and inspect token claims programmatically. It handles the parsing, expiration math, and formatting in one step, saving you from writing custom shell scripts.

Run deterministic JWT and base64 decoding directly in your terminal using Claude Code.

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Connect JWT & Base64 Decoder MCP to Claude Code

Create your Vinkius account to connect JWT & Base64 Decoder to Claude Code and route execution through our secure gateway. The platform manages server hosting, runtime updates, and security layers. Configuration requires no manual server provisioning.

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Setup JWT & Base64 Decoder with Claude Code

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Parse tokens from the command line

Your agent uses `decode_jwt_token` to extract headers, payloads, and expiration dates from raw tokens in your terminal. There is no need to pipe outputs to external web decoders or open a browser. The tool splits the token parts and outputs clean JSON directly to your shell. This is built for terminal workflows where speed and accuracy are critical. Your agent reads the token from your command history or environment variables, runs the tool, and shows you the decoded claims instantly.

Decode base64 strings inside Claude Code

Your agent uses `decode_base64_string` to translate encoded text back into raw UTF-8 format. This tool handles basic auth headers, Kubernetes secrets, or raw payload blocks that clutter your terminal logs. It provides a deterministic way to inspect encoded data without relying on shaky shell scripts. By running this server, your agent avoids math errors that occur when LLMs try to decode base64 natively. You get the exact string representation every single time.

Automate auth audits with this MCP Server

Your agent uses `decode_jwt_token` and `decode_base64_string` to audit tokens during deployment scripts or local testing. It can grab a JWT from a running container, decode the payload to verify the scopes, and alert you if the expiration date is misconfigured. This keeps your deployment pipelines secure and predictable. Using this headless setup allows you to run auth audits in SSH sessions or cron jobs. The tool integrates into your existing command-line environment, providing immediate feedback without manual UI interactions.

Setup guide

Set up JWT & Base64 Decoder MCP in Claude Code

Prerequisites

Claude Code CLI installed (npm install -g @anthropic-ai/claude-code)
Active Vinkius subscription with a valid endpoint token

1

Run the add command

Open your terminal and run the command shown on the right. Replace [YOUR_TOKEN_HERE] with your endpoint token from cloud.vinkius.com. Use --scope user to make it available across all projects.
2

Verify the connection

Start a Claude Code session and type /mcp to list connected servers. You should see jwt-base64-decoder-mcp with a green status indicator.
3

Start using tools

Ask Claude Code something like "Check my latest JWT & Base64 Decoder transactions." It will automatically discover and invoke the available JWT & Base64 Decoder tools.

Terminal

claude mcp add --transport http jwt-base64-decoder-mcp https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp

Get your connection token →

Prerequisites

Claude Code CLI installed
Active Vinkius subscription with a valid endpoint token

1

Open the config file

Create or edit .mcp.json in your project root for project-level scope, or ~/.claude.json for user-level scope.
2

Add the JWT & Base64 Decoder MCP

Paste the JSON snippet shown on the right into the mcpServers object. Replace [YOUR_TOKEN_HERE] with your endpoint token from cloud.vinkius.com.
3

Restart Claude Code

Start a new Claude Code session. Type /mcp to confirm the server is connected. The tools will be automatically available in your conversation.

.mcp.json

{
  "mcpServers": {
    "jwt-base64-decoder-mcp": {
      "type": "url",
      "url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp"
    }
  }
}

Get your connection token →

Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by JWT Decoder. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.

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Common questions about JWT & Base64 Decoder MCP in Claude Code

Run `claude mcp add --transport http jwt-base64-decoder -- ` in your terminal. You can verify the installation by running `claude mcp list` to see the active tools.

No. The `decode_jwt_token` tool only parses standard, unencrypted JWS tokens. It splits the token into its three base64url-encoded parts and decodes them, but it cannot decrypt JWE tokens that require private keys.

No. This MCP Server only performs deterministic decoding of the payload and header. It does not validate the cryptographic signature, so you must not assume a decoded token is cryptographically valid.

While you can use `openssl` or `base64` commands, this MCP Server lets Claude Code decode and inspect token claims programmatically. It handles the parsing, expiration math, and formatting in one step, saving you from writing custom shell scripts.

All decoding operations run inside Vinkius's secure, ephemeral V8 isolate sandbox. Your raw JWTs and base64 strings are processed in memory and never written to disk, ensuring your authentication tokens remain completely private.

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