JWT decoder. Decode and inspect JSON Web Token headers, payloads, and signatures instantly in your browser.
100% browser-based — your data never leaves your device
Decode and inspect JWT tokens instantly.
Copy the full JWT (including all 3 dot-separated parts) and paste it into the input field.
Press the Decode Token button to parse the header, payload, and signature.
Review the decoded header (algorithm, type) and payload (claims like sub, exp, iat) in formatted JSON.
Ctrl+Enter to decode
Decode and inspect JWT tokens instantly.
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Follow these steps to inspect and debug JSON Web Tokens without exposing your secrets:
All decoding happens locally using base64 decoding. Your tokens are never sent to any server.
JWT tokens often contain user identity data, session information, API permissions, and authentication credentials. Sending these tokens to external decoding services exposes your entire authentication state to third parties.
This JWT Decoder performs base64url decoding entirely in your browser. Your tokens, secrets, and authentication data never leave your device, making it safe for debugging production tokens and testing authentication flows.
JWT Decoder is a free online security tool that decode and inspect jwt tokens instantly. It works entirely in your browser — no downloads, no installations, and no server uploads required. security engineers, backend developers, system administrators use JWT Decoder when they need a fast, privacy-respecting way to process security data without installing additional software. It supports capabilities such as header inspection, payload claims, signature display. Additional features include local processing. Common use cases include inspecting jwt tokens during api authentication debugging, verifying jwt claim values and expiration times, analyzing jwt structure for security auditing. All processing happens locally using modern browser APIs, which means your data never leaves your device. This makes JWT Decoder ideal for working with sensitive data, proprietary code, or any situation where privacy matters.
JWT Decoder is a free online security tool that helps you decode and inspect jwt tokens instantly. Key capabilities include header inspection, payload claims, signature display. All processing is done locally in your browser — no data is uploaded, stored, or shared with any server. There are no sign-ups, no file size limits, and no hidden charges. It is commonly used to inspecting jwt tokens during api authentication debugging.
Copy the full JWT (including all 3 dot-separated parts) and paste it into the input field.
Press the Decode Token button to parse the header, payload, and signature.
Review the decoded header (algorithm, type) and payload (claims like sub, exp, iat) in formatted JSON.
| Category | Details |
|---|---|
| Input Limits | Maximum input size: Browser memory bound |
| Key sizes: 128–4096 bits (algorithm dependent) | |
| Supported Formats | JWT (RFC 7519), JWS (RFC 7515), JWE (RFC 7516), JWK (RFC 7517), Base64, JSON |
| Browser Engine |
|
All operations run entirely in your browser using built-in Security APIs. No server uploads, no data storage, and no third-party requests.
JWT Decoder is ideal when you need to inspecting jwt tokens during api authentication debugging without installing software or uploading data to a server. Since everything runs in your browser, there is no setup time and no risk of your data being stored on external servers. For for command-line cryptographic operations, consider using OpenSSL CLI. For for enterprise secret management, HashiCorp Vault may be a better fit. JWT Decoder fills the gap between heavyweight desktop tools and insecure online services that require uploading your data.
No. JWT Decoder processes everything entirely in your browser using JavaScript. Nothing you type, paste, or upload is ever transmitted to any server. Your data never leaves your device.
Yes. This tool only decodes — it does not verify signatures or send tokens to any server.
No. Signature verification requires the secret or public key used to sign the token.
View the token type and signing algorithm from the JWT header.
Decode and format the payload with user data, expiration (exp), issued-at (iat), and custom claims.
View the JWT signature portion. Note: decoding only, not signature verification.
Your JWT token is decoded entirely in your browser.
JWT Decoder is useful in a variety of scenarios across different workflows:
Inspecting JWT tokens during API authentication debugging
Verifying JWT claim values and expiration times
Analyzing JWT structure for security auditing
JWT payloads are base64-encoded, not encrypted. Anyone with the token can read the claims. Never store sensitive data in a JWT payload.
Always verify the alg header matches expectations. Some attacks exploit algorithm confusion by changing alg to 'none'.
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