JWT & Base64 Decoder MCP. Inspect tokens and decode opaque data streams.
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JWT & Base64 Decoder uses native binary methods to read encoded data streams. It instantly decodes complex JWT tokens into readable headers and payloads, while also handling general Base64 strings with precise UTF-8 output.
This MCP eliminates guesswork when inspecting authentication tokens or raw payload data.
What your AI agents can do
Decode base64 string
Decodes any Base64 string deterministically into plain UTF-8 text for general data inspection.
Decode jwt token
Decodes a complete JWT token, extracting the header and payload while calculating the exact expiration date.
Pass a raw Base64 text string to deterministically decode it into plain UTF-8 readable text.
Process a full JWT token, extracting the header, payload, and calculating the exact expiration date for immediate status checks.
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Supported MCP Clients
OAuth 2.0 Compatible Gemini Waiting for input…
JWT & Base64 Decoder: 2 Tools
Use these two tools to decode encoded strings, extract JWT claims, and inspect raw data payloads deterministically.
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Add this MCP to Claude, Cursor, or Windsurf and your AI stops guessing. It gets real tools to look things up, take action, and handle the stuff you keep doing by hand.
Start using JWT & Base64 Decoder on Vinkius019e38b2decode base64 string
Decodes any Base64 string deterministically into plain UTF-8 text for general data inspection.
019e38b2decode jwt token
Decodes a complete JWT token, extracting the header and payload while calculating the exact expiration date.
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Works with Claude, ChatGPT, Cursor, and more
The Model Context Protocol standardizes how applications expose capabilities to LLMs. Instead of operating in isolation, your AI gains direct access to external platforms, live data, and real-world actions through secure, standardized connections.
This server provides 2 capabilities that interface natively with Claude, ChatGPT, Cursor, and any MCP client. No middleware. No custom integration required.
Parsing encoded strings used to be a manual pain point.
Today, if you need to check the contents of an intercepted token or a raw API payload, you often end up running multiple scripts locally. You copy the string into one tool for Base64 decoding, then run it through another script just to split and read the JWT header/payload. It's tedious, error-prone, and you always risk missing critical context like the exact expiration date.
With this MCP, your agent handles the whole sequence automatically. You pass the opaque string once; the system returns a single, structured JSON object with all necessary claims, including calculated expiry time. The result is clean data ready to use.
Decode JWT & Base64 Data Streams
You instantly eliminate the need for multiple decoding steps or custom parsing logic. Instead of writing code that handles both general Base64 and structured JWTs, you let your agent call `decode_jwt_token` directly. It’s a single, reliable operation.
The difference is reliability. You get deterministic results every time with zero risk of human error in the decoding pipeline.
What you can do with this MCP connector
Okay, so you've got a token or some API response that’s just a string of gibberish—Base64 encoded, maybe wrapped in JWT format. You need to see what's inside without breaking anything. This MCP lets your agent pull apart those opaque strings using native methods, giving you the raw JSON payload and all the structured claims.
It handles everything from basic Base64 decoding to extracting specific details like user IDs or expiration timestamps from a full JWT token. If you're working with data that came encoded, this is what you use. You just pass the string, and your agent gets back clean, usable data for analysis, letting your entire workflow run smoothly through the Vinkius catalog.
019e38b3-0b52-7326-932e-614ff6bf398b 
How JWT & Base64 Decoder MCP Works
- 1 Provide your agent with the raw Base64 string or the complete JWT token you need to inspect.
- 2 The MCP processes the input using native binary functions, separating and validating the components of the encoded data.
- 3 Your agent receives a clean JSON structure containing decoded payloads, specific claims (like 'sub'), and calculated expiration timestamps.
The bottom line is you feed it an encoded string, and it reliably outputs structured, readable data.
Who Is JWT & Base64 Decoder MCP For?
The security engineer who needs to quickly inspect a suspicious token without running a local decoding script. The backend developer debugging API authentication flows. Any ops specialist that needs to verify session data passed through message queues.
Inspects intercepted JWT tokens to confirm claims, check for proper expiration dates, or validate if a token payload contains unexpected user identifiers.
Debugs authentication middleware by passing raw Base64 payloads received from external services to ensure the data integrity and correct JSON structure before processing.
Validates session tokens captured in logs, using this MCP to decode them quickly and verify if they are still active or have expired.
What Changes When You Connect
- Stop guessing about expired tokens. The
decode_jwt_tokentool calculates the precise expiration date, eliminating guesswork from your agent's output. - You get raw access to encoded data without boilerplate code. Use
decode_base64_stringto handle any non-JWT Base64 payload immediately. - It handles structured authentication data reliably. Instead of writing custom parsing logic, let the MCP extract claims like 'sub' and 'exp'.
- The process is deterministic. The output for both tools relies on native binary buffers, ensuring consistent results every time.
- You bypass client-side limitations. Your agent accesses powerful decoding utilities regardless of whether it’s running in an IDE or a terminal.
Real-World Use Cases
Verifying suspicious API calls
A security analyst receives a log entry containing a JWT token and needs to check if it's valid. They pass the raw token, and using decode_jwt_token, their agent extracts the payload and confirms both the user ID and whether or not the token has already expired.
Debugging external service payloads
A backend developer receives a Base64-encoded chunk of data from an external API that isn't JSON. They use decode_base64_string to reliably convert the raw string into readable UTF-8 text for inspection.
Auditing session tokens
A DevOps engineer needs to check a captured, non-JWT base64 session identifier. They feed it into decode_base64_string and get the plain underlying data immediately, allowing them to confirm if the user was active at that time.
The Tradeoffs
Using generic string manipulation
Trying to decode a JWT token by simply splitting it on dots and then using standard base64 functions. This ignores the structure and doesn't calculate expiration.
→
Use decode_jwt_token instead. It handles the full three-part JWT format and, crucially, calculates the exact 'exp' claim for you.
Assuming Base64 is encryption
Believing that because a payload looks encoded, it must be secure or contain sensitive data that requires complex decryption. It’s just encoding.
→
Use decode_base64_string to see the raw text content. Remember: Base64 is only an encoding scheme; it provides zero confidentiality.
Ignoring payload structure
Passing a complex token and only getting back a jumbled mess of characters, making it impossible to determine if the user ID or expiration date is present.
→
Always use decode_jwt_token. It guarantees extraction of key claims like 'sub' and provides structured JSON output.
When It Fits, When It Doesn't
Use this MCP if your core task involves inspecting, validating, or extracting data from encoded strings (JWT or Base64). Specifically, use decode_jwt_token when you must validate authentication tokens because it handles the full structure and calculates expiration dates. Use decode_base64_string for any general-purpose decoding where the input isn't necessarily a JWT. Don't use this if your data is encrypted (you need an actual decryption key/tool) or if you are simply validating that a string looks like Base64; these tools decode it, they don't validate its format alone.
Common Questions About JWT & Base64 Decoder MCP
How does decode_base64_string handle non-JWT data? +
It treats the input as a generic Base64 string, deterministically converting it into plain UTF-8 text. This lets you inspect any kind of raw encoded payload, not just tokens.
Does decode_jwt_token verify the token signature? +
No. It decodes the content for inspection only and does not attempt to validate the cryptographic signature. It simply extracts the header and payload data for review.
What information can I get from decode_jwt_token? +
You retrieve the decoded JSON contents of the header, the main payload body, and most importantly, a precise calculation of the token's expiration date.
Can this MCP handle large data payloads? +
Yes. It uses native binary buffers designed for precision decoding, allowing it to reliably process complex, long-form encoded strings without failure.
If I use decode_jwt_token, does it validate the token's signature or issuer? +
No. This MCP only decodes the content deterministically. It parses the header and payload sections of the JWT, but it never validates the cryptographic signature or checks for an issuer claim.
When I use decode_base64_string, what happens if the input isn't valid Base64? +
The tool handles malformed inputs by returning a specific decoding failure. It won't crash; instead, it signals that the provided string does not conform to the required Base64 standard.
Can decode_jwt_token extract data from tokens with non-standard claims? +
Yes. You can get all key-value pairs present in the payload, including custom or non-standard claims. The output JSON structure will reflect exactly what was provided in the token.
If I use decode_base64_string on a JWT, is that sufficient for my needs? +
No. Using decode_base64_string treats the entire input as raw text without context. Use decode_jwt_token when you need the structured extraction of headers and accurate expiration math.
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.
Use it with your favorite AI tools
Connect this server to Cursor, Claude, VS Code, and more.