JWT DecoderDecode and inspect JSON Web Tokens — view header, payload, and expiration status.
JWT Decoder
Decode and inspect JSON Web Tokens — view header, payload, and expiration status.
Paste Token
Paste your JWT token.
View Decoded
Header, payload, signature appear instantly.
Copy Parts
Copy any section.
What Is JWT Decoder?
JSON Web Tokens (JWT) are compact, URL-safe tokens for authentication and information exchange. A JWT has three Base64URL-encoded parts: header (algorithm/type), payload (claims like subject, issuer, expiration), and signature. This tool decodes JWTs in your browser, displaying each part as readable JSON and checking expiration status. JWTs are used in OAuth 2.0, OpenID Connect, and modern API auth. Understanding their contents is essential for debugging auth flows and verifying claims. No data leaves your browser.
Why Use Our JWT Decoder?
- Instant decoding with real-time display
- Shows expiration status and all claims
- 100% client-side — tokens never leave your browser
- Free with no signup required
Common Use Cases
API Debugging
Inspect access/refresh tokens from OAuth flows.
Security Audit
Review JWT claims and expiration.
Development
Debug authentication issues.
Education
Learn JWT structure.
Technical Guide
JWTs use Base64URL encoding (RFC 7519). The header typically contains alg and typ fields. The payload carries registered claims (iss, sub, exp, iat) and custom claims. The signature is HMAC or RSA over the encoded header.payload. This decoder splits on dots, Base64URL-decodes each part, parses JSON, and checks exp against current time. Supports standard and URL-safe Base64 variants.
Tips & Best Practices
- 1Check exp claim for validity
- 2The alg field shows signing algorithm
- 3JWTs are not encrypted — anyone can read the payload
- 4Use JWT Validator for signature verification
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Encoding & CryptoFrequently Asked Questions
QIs this tool free?
QIs my data secure?
QCan it verify signatures?
QWhat formats are supported?
QDoes it check expiration?
About JWT Decoder
JWT Decoder is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.