Decode and validate JSON Web Tokens with signature verification
Paste a JWT token above to decode and validate it.
The header typically contains token type (JWT) and signing algorithm. Default values are usually sufficient.
Add claims (data) to the payload: user ID, username, roles, expiration time, or other custom claims as needed.
Enter your secret key for signing the token. Keep this secret secure - it's used to verify token authenticity.
Select signing algorithm: HS256 (HMAC), RS256 (RSA), or others. HS256 is common for symmetric keys, RS256 for asymmetric.
Click generate to create the JWT. The token will be displayed in encoded format.
Use the decoder to verify token contents, check expiration, or debug token issues.
Verify the token signature using your secret key to ensure the token hasn't been tampered with.
Include the JWT in API requests (usually in Authorization header) for authentication and authorization.
JWTs are used for authentication (proving identity) and authorization (determining permissions) in web applications and APIs.
JWTs are secure when properly implemented with strong secret keys, HTTPS, and appropriate expiration times. Never expose secret keys.
Include user ID, username, roles, and expiration time. Avoid sensitive data like passwords. Keep payloads small for performance.
Short-lived tokens (15 minutes to 1 hour) are more secure. Use refresh tokens for longer sessions. Adjust based on your security requirements.
Yes, JWTs can be decoded to view contents, but you need the secret key to verify the signature and ensure authenticity.
HS256 uses a shared secret key (symmetric). RS256 uses a private/public key pair (asymmetric). RS256 is better for distributed systems.
JWTs are stateless, so they can't be directly revoked. Use short expiration times, maintain a blacklist, or use refresh tokens for revocation.
Store JWTs securely: in httpOnly cookies (most secure), localStorage (less secure), or memory. Avoid XSS vulnerabilities.
Use short expiration times, implement token refresh, monitor for suspicious activity, and consider additional security measures like IP validation.
Yes, JWTs are commonly used for API authentication. Include the token in the Authorization header: "Bearer <token>".
Set access tokens to expire in 15-30 minutes. Use refresh tokens for longer sessions. Short-lived tokens limit the damage window if a token is compromised.
Never transmit JWTs over plain HTTP. Tokens sent in the clear can be intercepted and replayed. Enforce HTTPS everywhere tokens are transmitted or received.
Use asymmetric signing (RS256/ES256) so only the server with the private key can create tokens, while anyone with the public key can verify them. HS256 shares the secret with all verifiers.
Always verify iss (issuer), aud (audience), exp (expiration), and nbf (not before) claims on the server side. Never trust a token without full validation.
JWT payloads are Base64-encoded, not encrypted. Anyone can decode and read them. Never include passwords, credit card numbers, or other secrets in token claims.
Set the typ header to distinguish between token types (access vs refresh). This prevents token confusion attacks where a refresh token is used as an access token.
Maintain a blocklist or use short-lived tokens with refresh rotation. Without revocation, compromised tokens remain valid until they expire naturally.
Store JWTs in httpOnly, Secure, SameSite cookies rather than localStorage. LocalStorage is accessible via JavaScript and vulnerable to XSS attacks. HttpOnly cookies are not accessible to scripts and are automatically sent with requests.
Rotate refresh tokens on every use (refresh token rotation). If a refresh token is stolen and used, the server detects reuse when the legitimate user tries to refresh, and can invalidate the entire token family.
Use a well-maintained JWT library for your language (e.g., jsonwebtoken for Node.js, php-jwt for PHP) rather than writing your own parsing and verification logic. Custom implementations are a common source of critical security vulnerabilities.
Discover the JaneX JWT benefits and how it enhances secure token authentication for developers in 2026.
Discover the top JaneX JWT applications that enhance security and efficiency for developers in 2026.
Understand JSON Web Tokens, how they work for authentication, and best practices.
Explore other powerful tools from JaneX
Encode and decode Base64 strings, text, images, and files instantly.
Generate MD5, SHA, bcrypt, and Argon2 hashes for text, files, and URLs.
Convert text between uppercase, lowercase, title case, camelCase, PascalCase, snake_case, kebab-case, and sentence case instantly.
Format, minify, validate JSON, and convert between JSON and YAML. Tree view and schema validation.
Generate strong, secure passwords with customizable length and character options.
Create QR codes for URLs, WiFi networks, contacts, emails, and more instantly.
Compress JPEG, PNG, and WebP images to reduce file size.
Resize images online with aspect ratio control.
Convert images between JPG, PNG, WebP, and GIF formats.
Convert between units of length, mass, temperature, and time instantly.
Count characters, words, sentences, paragraphs, and lines instantly.
Generate placeholder text in multiple formats: paragraphs, sentences, words, lists, headings, and mixed content.
Generate perfect color palettes using algorithms, extract colors from images, or create manually. Export to CSS, SCSS, JSON.
Create professional PDF invoices in seconds. Free, fast, and with multiple currency support.
Build stunning CVs with our easy-to-use generator. Multiple templates, instant PDF download.
Generate barcodes in multiple formats: EAN-13, UPC-A, Code128, Code39, ITF-14, and Codabar.
Calculate your Body Mass Index instantly with metric and imperial units.
Shorten URLs with analytics and custom slugs.
Merge multiple PDF files into one. Reorder with drag and drop.
Split PDF files by selecting pages. Visual thumbnails and extraction.
Compress PDF files to reduce size. Strip metadata and optimize.
Calculate mortgage and personal loan payments. Monthly payment, total interest, and amortization schedule.
Track your menstrual cycle, calculate fertile window, and predict ovulation dates.
Remove image backgrounds with AI. Transparent PNG or WebP export. Runs in your browser.
Weather forecast for any city.
Free daily horoscope by zodiac sign. General, love, career, and health.
Search recipes by ingredients, explore food products with Nutri-Score, and get AI health insights.