在线免费JWT解码器
即时解码和验证JWT令牌，无需服务器。
Frequently Asked Questions
What is a JWT and what does it contain?
JWT (JSON Web Token) is a compact, self-contained token format. It has three base64url-encoded parts separated by dots: Header (algorithm and type) . Payload (claims — user data, expiry, issuer) . Signature (verification).
Is it safe to paste JWTs into this tool?
The decoding runs entirely in your browser — no token is sent to any server. However, avoid pasting production access tokens for active accounts in any online tool as a general security practice.
What are common JWT claims (iss, sub, exp, iat)?
iss = issuer (who created the token). sub = subject (user ID). exp = expiration time (Unix timestamp). iat = issued at (creation time). nbf = not valid before. aud = audience (intended recipient).
Can I verify a JWT signature with this tool?
Yes. For HMAC algorithms (HS256, HS384, HS512), enter your shared secret. For RSA/ECDSA (RS256, ES256), paste your public key. The tool computes and compares signatures to verify authenticity.
Why can I decode a JWT without knowing the secret?
The header and payload are base64url-encoded, not encrypted. Anyone can decode them. The signature protects integrity — without the secret/key, you can't forge a valid JWT or verify an existing one.
Is the JWT解码器 free to use?
Yes, the JWT解码器 on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.
How does the JWT解码器 work?
即时解码和验证JWT令牌，无需服务器。 No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.
Do I need to install anything to use the JWT解码器?
No installation needed. The JWT解码器 runs entirely in your web browser on any device — desktop, tablet, or mobile.
Is my data safe when using the JWT解码器?
Completely safe. The JWT解码器 processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Does the JWT解码器 work offline?
After the page loads for the first time, the JWT解码器 works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.
Can I use the JWT解码器 output in commercial projects?
Yes. The JWT解码器 is a utility tool and its output carries no licensing restrictions. You are free to use results in any project, commercial or personal.
Does the JWT解码器 follow official standards?
Yes. The JWT解码器 is built to comply with the relevant industry standard or specification for this utility type. If you encounter an unexpected result, verify your input against the specification — edge cases outside the standard may produce undefined behaviour.
Does the JWT解码器 work on all browsers?
Yes. The JWT解码器 is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.
How do I save or export my results from the JWT解码器?
Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.