JWT Token Decoder
Decode and inspect JSON Web Tokens (JWT) client-side. Parse header, payload claims (iss, sub, exp, iat), and signature without sending tokens to any server.
1 How to Use JWT Token Decoder
- 1. Paste your JWT token.
- 2. Header and Payload JSON parse automatically in real-time.
- 3. Check human-readable expiration dates and claims.
⚙️ Cryptographic Specifications
- Algorithm
- RFC 7519
- Execution Engine
- Web Cryptography API (SubtleCrypto)
- Environment
- Client Browser Sandbox
- Network Telemetry
- 0 Bytes (Zero Server Transmission)
🛡️ Security & Compliance
Enterprise developers can safely execute this tool with production secrets. Because execution takes place entirely within your browser's local V8 JavaScript runtime, no payloads are transmitted over HTTP, cached on third-party proxies, or stored in server logs.
Verified Safe for SOC2, HIPAA, and GDPR developer compliance audits.
Frequently Asked Questions
Is it safe to paste production JWTs here?
Yes! Unlike other sites, WebCryptoTools does not send your token to any server or log it in analytics. Execution is 100% in-browser.
What do the three parts of a JWT represent?
Header (Algorithm & Token Type), Payload (User Claims & Permissions), and Signature (Tamper verification).
Related Cryptographic Tools
JWT Signature Verifier
Verify HMAC (HS256, HS384, HS512) or RSA/ECDSA signatures of JWT tokens client-side using Web Crypto API. Confirm payload integrity locally.
JWT Token Builder & Signer
Build and sign custom JSON Web Tokens (JWT) in your browser. Configure claims, expiration (exp), audience (aud), and sign with HS256 or RS256.
JWT Expiration & Claims Inspector
Inspect JWT expiration (exp), issued-at (iat), and not-before (nbf) timestamps with human-readable local time, countdown timers, and validity checks.