JSON Web Token Decoder

Decode the header and payload of a JWT (JSON Web Token) securely in your browser.

Input

Upload File

Output

Frequently Asked Questions

What is a JWT and why decode it?

A JWT (JSON Web Token) is a Base64-encoded token used for authentication and authorization in web applications. Decoding it reveals the header (algorithm info), payload (user claims, expiration, permissions), and allows developers to debug authentication issues without verifying the signature.

Who uses this tool professionally?

Backend developers debug authentication failures by inspecting JWT payload claims. Security auditors review JWT tokens for sensitive data exposure and weak algorithm usage. QA engineers verify that correct user roles and permissions are encoded in API authentication tokens.

Does it verify the JWT signature?

No. This tool decodes and displays the header and payload for inspection purposes only. Signature verification requires the signing secret or public key, which should never be entered into a web tool. Use your application's JWT library for signature verification.

Is my JWT kept private?

Yes. All decoding happens locally in your browser. JWT tokens containing authentication credentials and user claims are never transmitted to any server.

JSON Web Token Decoder

Decode the header and payload of a JWT (JSON Web Token) securely in your browser.

Key Capabilities

Decodes header, payload, and signature separately

The decoder splits and presents each section in a formatted, readable JSON view.

Token expiry and validity status

The tool checks the exp claim against the current time and displays whether the token is valid or expired.

Processes entirely in-browser for security

JWT tokens are decoded entirely in the browser using local JavaScript — the token never leaves your device.

How to Use

Paste your JWT

Copy the JWT token from your browser developer tools or API testing tool. Paste the full token.

Review the decoded sections

Check the header for signing algorithm and the payload for all claims.

Check expiry status

The expiry status banner shows whether the token is currently valid or expired.

Common Use Cases

Developers debugging authentication failuresA developer can check whether the token has expired or whether the correct claims are present.
Security engineers auditing JWT claimsA security engineer can verify that sensitive data is not being embedded unnecessarily in the payload.
QA engineers verifying token contentsA QA engineer can verify that correct user ID, roles, and permissions are present in each token.

Frequently Asked Questions

What is a JWT and why decode it?

Who uses this tool professionally?

Does it verify the JWT signature?

Is my JWT kept private?

Yes. All decoding happens locally in your browser. JWT tokens containing authentication credentials and user claims are never transmitted to any server.

Related Tools

CSV to JSON

Parse CSV files and convert them into formatted JSON arrays. Free and fast browser-based tool.

JSON to XML

Convert JSON objects into valid XML tags instantly. Free developer utility.

XML to JSON

Parse XML documents and convert them to readable JavaScript JSON objects. Free and private.

JSON to YAML

Convert JSON syntax to highly readable YAML format. 100% free client-side tool.

Developer Utilities — Data Format Conversion and Encoding

Understanding Data Serialization Formats

Software developers frequently work with structured data formats like JSON (JavaScript Object Notation), CSV (Comma-Separated Values), XML (Extensible Markup Language), and YAML (YAML Ain't Markup Language). Each format has different strengths: JSON is the standard for web APIs and configuration files. CSV is universally supported by spreadsheet applications. XML is used in enterprise systems and document formats. YAML is popular for human-readable configuration. Our conversion tools transform data between these formats instantly, handling edge cases like nested objects, special characters, and encoding differences.

Cryptographic Hash Functions

Hash functions like MD5, SHA-1, SHA-256, and SHA-512 convert any input data into a fixed-length string of characters called a hash or digest. These functions are one-way — you cannot reverse-engineer the original input from the hash. They are used for password storage, data integrity verification, digital signatures, and file deduplication. SHA-256 is the current standard for security-sensitive applications. MD5 and SHA-1 are considered cryptographically broken for security purposes but are still useful for checksums and non-security applications. All our hash generators run entirely in your browser — your data is never transmitted.

Text Encoding and Character Sets

Computers store text as numbers. ASCII maps 128 characters (English letters, digits, basic punctuation) to numbers 0-127. Unicode extends this to over 140,000 characters covering virtually every writing system on Earth. UTF-8 is the dominant encoding on the web, using 1-4 bytes per character. Base64 encoding converts binary data (like images or files) into a text-safe format using 64 printable ASCII characters. URL encoding replaces special characters with percent-encoded equivalents for safe transmission in web addresses. Our encoding tools handle all these transformations with proper error handling for malformed input.

Privacy for Developer Tools

All DoctorDocs developer tools process your data entirely in your browser using JavaScript. No API calls, no server uploads, no telemetry. This is critically important for developers working with sensitive data — API keys, database connection strings, configuration secrets, or proprietary code. When you paste a JSON payload to format it, or generate a SHA-256 hash of a password, the data exists only in your browser's memory. Close the tab and it is gone. This makes DoctorDocs developer tools safe to use with production data and secrets.