JWT Online Debugger & Decoder

Decode JSON Web Token headers and payloads with automatic validity and expiration countdown

100% Browser Local Computing: Zero Cloud Upload - Offline Capable

JWT 除錯驗證 100% Browser Local Computing

Enter JWT Token (three dot-separated segments)

Header.Payload.Signature

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkFsZXgiLCJpYXQiOjE1MTYyMzkwMjJ9.XbPfbIHMI6arZ3Y922BhjWgQzWXcXNrz0ogtVhfEd2o

HeaderHS256

{
  "alg": "HS256",
  "typ": "JWT"
}

Payload

Issued At (iat): 1/18/2018, 1:30:22 AM

{
  "sub": "1234567890",
  "name": "Alex",
  "iat": 1516239022
}

Signature

HMAC-SHA256 (base64url): XbPfbIHMI6arZ3Y922BhjWgQzWXcXNrz0ogtVhfEd2o

Offline client-side JWT parser. Decode header, payload claims, and check expiration (exp) and issued-at (iat) timestamps securely.

Frequently Asked Questions

Is it safe to paste JWT tokens into this online tool?

Completely safe. Processing happens entirely in your local browser window without transmitting tokens to any server.

How does the tool check token expiration?

It parses exp and nbf timestamp claims and compares them to your current UTC system clock.

Automatic type inference with Serde macro injection and camelCase to snake_case conversions

Infers nested types and generates TypeScript interfaces and Zod schema validators

Generate Java 17 Records and POJO classes with automatic Jackson annotations and Lombok tags

Fast percent-encoding conversion with component mode and full URL decoding

Bidirectional conversion between Unicode characters, \uXXXX, and HTML entities

Accurate syntax error line pointers, instant indentation beautification, and minification