Free Online Developer Tools – ULID, UUID, NanoID, CUID, Snowflake ID, JWT Decoder, Base64, JSON Formatter & More

ULID Generator

Generate Universally Unique Lexicographically Sortable Identifiers with high performance

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JWT Decoder Online

Decode any JSON Web Token (JWT) instantly. View the header algorithm, payload claims (exp, iat, sub), and validate structure - all in your browser, no data sent to any server.

JWT Decoder & Debugger

Parse JSON Web Tokens, inspect claims, and scan for common security vulnerabilities

100% Client-Side & Secure: Your token is parsed entirely within your browser. We never send, store, or log your tokens or secrets on any server. Sharing links store configurations inside the URL hash, keeping your token client-side only.
Real-time Security Warnings
Paste a JWT token to scan its header and payload for known security weaknesses.
JWT Signature Verification
Paste JWT and enter secret to verify
Header (Algorithm & Token Type)
// Paste a token to inspect...
Payload (Claims & Metadata)
// Paste a token to inspect...

What is a JWT Token?

A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication and information exchange. It consists of three Base64URL-encoded parts separated by dots: header.payload.signature.

How to Decode a JWT

  1. Paste your JWT token into the input field above
  2. The decoder instantly splits and Base64URL-decodes each part
  3. View header (algorithm, token type), payload (claims), and signature
  4. Check expiry time (exp) and issued-at (iat) in human-readable format

Common JWT Claims

iss

Issuer

sub

Subject

aud

Audience

exp

Expiration time

iat

Issued at

jti

JWT ID

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