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JWT Encoder & Decoder – Debug JSON Web Tokens Online

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Encode, decode, and debug JSON Web Tokens with signature verification. Complete JWT toolkit with HMAC SHA-256/384/512 support for secure authentication.

JWT Encoder & Decoder

Create and verify JSON Web Tokens with HMAC signing

Used to sign the token. Never share your secret key.

What is JWT Encoder & Decoder?

Create, decode, and debug JWTs with custom headers and payloads using HMAC SHA-256/384/512. Verify signatures, validate expiration (exp), not-before (nbf), and issued-at (iat) times. Essential for debugging authentication, testing OAuth implementations, and validating API integrations. All processing is client-side using Web Crypto API.

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JWT Encoder & Decoder Features

Encode & Decode

Create JWTs or decode existing tokens

Signature Verification

Verify authenticity with HMAC SHA-256/384/512

Claims Validation

Automatic validation of exp, nbf, iat timestamps

Client-Side

Maximum security – no server uploads

JWT Encoder & Decoder FAQ

Yes. All processing happens in your browser using Web Crypto API. Tokens and secrets never leave your device. However, always be cautious with production secrets.
Yes. Provide your secret key to verify JWT signatures using HMAC SHA-256/384/512. The tool indicates valid (✓) or invalid (✗) signatures.
HS256 (HMAC SHA-256), HS384 (HMAC SHA-384), and HS512 (HMAC SHA-512) – the most common JWT algorithms.