# JWT & Base64 Decoder MCP for AI Agents AI Agent Connect

> JWT & Base64 Decoder lets you instantly turn messy Base64 strings and JWT tokens into readable JSON. It handles the math for expiration dates and headers perfectly so your AI agent doesn't have to guess what's inside a token. It's built for precision and developer speed.

## Overview
- **Category:** developer-tools
- **Price:** Free
- **Endpoint:** https://edge.vinkius.com/vk_preview_JtisWyM2L8SwCbAosdXvoaNUkIeJdtsNTEISeftK/ai-agent-connect
- **Tags:** jwt, base64, token-decoding, authentication, payload-inspection, binary-data

## Description

When you're debugging auth flows, the last thing you want is your AI agent making up a close enough date for a token expiration. This Connector handles the heavy lifting of binary decoding. It takes raw strings and gives you back clean, accurate data. You can use it to inspect headers, grab user IDs from payloads, or check exactly when a session ends without having to copy and paste everything into an external web tool. Because it uses native Node buffers, the results are consistent every time. It's one of the reliable developer tools you'll find in the Vinkius catalog, making it easy to plug into your existing agent setup. Instead of trusting a hallucination, you're getting the actual facts from the token. It keeps your security audits and debugging sessions grounded in reality. You get clear text and structured JSON without the fluff.

## Tools

### decode_base64_string
Converts raw Base64 strings into readable UTF-8 text. It's perfect for quickly reading encoded payloads.

### decode_jwt_token
Breaks down a JWT into its header and payload. It also calculates the exact expiration timestamp for you.

## Prompt Examples

**Prompt:** 
```
Check if this token is expired: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkiLCJleHAiOjE2ODkzMzI1NjF9.SflKxw==
```

**Response:** 
```
✅ **Token Status:**

This token is **expired**.

*   **Expiration Date:** 2023-02-24
*   **User ID (sub):** 123456789

The `exp` claim indicates the token was valid until the date listed above.
```

**Prompt:** 
```
What's inside this Base64 string? SGVsbG8gV29ybGQ=
```

**Response:** 
```
✅ **Decoded Content:**

`Hello World`
```

**Prompt:** 
```
Extract the user ID from this JWT: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c3JfOTk4M2E1IiwiZW5hb3V0Ijoiam9obiJ9.signature
```

**Response:** 
```
✅ **Payload Extraction:**

*   **User ID (sub):** `usr_9983a5`
*   **Email:** `john`
```

## Capabilities

### Convert Base64 to UTF-8 text
Turn encoded strings into readable plain text.

### Extract JWT headers and payloads
Break down a JWT into its constituent parts for inspection.

### Calculate exact token expiration dates
Get the precise timestamp for when a token expires.

### Parse raw strings into JSON
Convert encoded data into structured JSON objects.

### Inspect authentication claims
Quickly view user IDs, roles, and other claims within a token.

## Use Cases

### Auditing a failed login
A dev asks the agent to check why a token failed. The agent uses decode_jwt_token to find an expired exp claim.

### Inspecting API responses
A QA tester gets a Base64 blob from a webhook and asks the agent to use decode_base64_string to see the contents.

### Debugging Auth Headers
A backend dev wants to see the sub claim in a Bearer token and has the agent decode it on the fly.

### Verifying Webhooks
A developer needs to check if a signature-less payload contains the correct metadata from a third party.

## Benefits

- Stop LLM hallucinations by using native Node buffers for all decoding tasks via decode_base64_string.
- Get exact expiration dates instantly with decode_jwt_token instead of guessing.
- Speed up security audits by inspecting claims directly in your chat window.
- Remove the need to switch tabs to external websites for every single token check.
- Ensure your agent handles binary data correctly without losing character encoding.
- Verify payload integrity quickly to catch bugs in your auth middleware.

## How It Works

The bottom line is you get 100% accurate data from encoded strings without any AI guesswork.

1. Provide your agent with a raw JWT or Base64 string.
2. The Connector processes the string using native buffers for high precision.
3. You get back a clean JSON object with all decoded fields.

## Frequently Asked Questions

**Can the JWT & Base64 Decoder handle large payloads?**
Yes, it handles standard JWTs and Base64 strings using native buffers, making it reliable for typical production payloads.

**Does the JWT & Base64 Decoder verify signatures?**
No, this tool is strictly for decoding. It helps you see what's inside the token without performing security validation.

**Can I use JWT & Base64 Decoder for debugging?**
Absolutely. It's a primary tool for developers who need to see auth claims, headers, and timestamps while debugging APIs.

**Will JWT & Base64 Decoder hallucinate dates?**
No. It calculates the exact expiration date from the 'exp' claim using native math, ensuring you get the correct timestamp every time.

**Is JWT & Base64 Decoder safe for production use?**
It is safe for inspection purposes. Since it only decodes data and doesn't perform actions, it's a great way to audit your logs.

**Is it secure?**
Yes, decoding runs completely local.

**Does it verify the JWT signature?**
No, this is a strict decoder for reading payloads, not an authentication gateway.

**Can it decode hex as well?**
It is specialized in Base64 and JWT headers/payloads.