JWT Decoder
Inspect tokens locally · no leakage
We never validate the signature here, that needs the secret/key. Decoding is local; the token never uploads.
Expiry
Valid · expires 5/18/2033, 3:33:20 AM
Algorithm
HS256
Type
JWT
Header
{
"alg": "HS256",
"typ": "JWT"
}Payload
{
"sub": "user_123",
"name": "Alice",
"iat": 1700000000,
"exp": 2000000000,
"role": "admin"
}Signature (base64url)
fake-signature-for-demo
Signatures need the secret (HMAC) or public key (RSA/ECDSA) to verify. We don't do that here on purpose, keeps the tool 100% client-side and prevents secret leakage.
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Questions
- Is JWT Decoder free?
- Yes. JWT Decoder is completely free, with no account, no sign-up, and no usage limits. It runs entirely in your browser.
- Do my files get uploaded when I use JWT Decoder?
- No. JWT Decoder processes everything on your device, so your files and text never leave your browser. You can verify it yourself: open your browser's Network tab and you'll see no uploads.
- How do I use JWT Decoder?
- Open JWT Decoder in your browser, no install or sign-up needed, then paste, type, or drop in your input and the result appears instantly. Paste a JWT, see decoded header, payload, signature, plus expiry status. Detects standard claims (iat, exp, nbf), shows expired vs valid clearly. Browser-only, your token never uploads.
- Is there a file size limit in JWT Decoder?
- There's no hard file or text size limit. Because JWT Decoder runs locally in your browser, the only ceiling is your device's available memory, and everyday files process instantly.