JWT Decoder
Decode and inspect JSON Web Tokens — view header, payload claims, and expiration status.
Paste a JWT token to get started
Decode and inspect any JSON Web Token — view header algorithm, payload claims, expiration, and more.
Key Features
Payload Data Decoder
Decode web access key data payloads instantly. The tool translates encoded key strings to extract user details, email addresses, and account permissions, updating the results as you type to make testing simple. It reads data properties one-by-one, ensuring that complex details are translated into clean, structured tables that you can read in seconds. This helps developers check user logins and troubleshoot authentication setups quickly.
Token Header Checker
Inspect header parameters inside the security token block. The decoder shows the type of signature rules used (like HS256, RS256, or ES384), key codes, standard formats, and token options. This is helpful for checking login settings and ensuring the token options match your server configuration, avoiding validation failures and keeping configurations uniform.
Expiration Watcher
Monitor token validity periods dynamically. The validator checks expiration times, creation dates, and activation thresholds, converting complex timestamps into standard calendar dates and times with live countdown timers. It highlights expired tokens visually with a warning message, helping developers find login session timeouts and trace authentication bugs.
JSON Folder Explorer
Explore token claims using our visual data folder tree. You can search through nested information, filter user permissions, collapse data folders, and copy specific fields to make debugging fast and simple. This helps front-end developers locate user details, verify settings, and check permissions without scanning lines of raw code.
Token Parts Splitter
Analyze the token structure to make sure it is correct. The tool splits the token string into Header, Payload, and Signature parts, displaying them in a color-coded layout. This makes it easy to check the boundaries and inspect the components, allowing engineers to verify formatting standards and check structural rules.
Claims Dictionary
Understand token fields using the built-in terminology guide. Get clear explanations of standard fields (like subject IDs, issuers, and client targets) to understand the data inside your tokens. This dictionary guides developers through token properties, explaining standard parameters and making verification safe and easy.
Private Decoder
Decode authentication tokens securely. All string splitting, Base64URL decoding, claims formatting, and validity checking run locally in the browser, keeping credentials off external networks. This protects developers from leaks of sensitive tokens, private claims, customer emails, or user data.
History Logs
Manage token testing history. Store previous sessions in a local logs panel, restore configurations with one click, or export JSON claims to files. The history tracker keeps tokens organized locally, allowing you to restore values and run validation tests across multiple entries, simplifying workflows.
Usage Examples
Encoded: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
Decoded Header:
{
"alg": "HS256",
"typ": "JWT"
}Common Use Cases
Debugging SSO Configurations
When integrating authentication providers (like Auth0, Firebase, or Keycloak), verify that user attributes are mapped correctly. Decode ID tokens or access tokens to inspect groups and metadata, helping you configure application access controls. This validates claim mapping, ensures correct scope parameters, and speeds up Single Sign-On testing across staging environments, avoiding auth errors.
Verifying Token Expirations
Investigate authentication failures on frontend API feeds. Paste access tokens into the decoder to check expiration timestamps (exp) and relative lifetimes, verifying that client clocks and refresh token calls are working correctly. It highlights timing offsets, checking if sessions have timed out or if client systems require token updates, aiding troubleshooting.
Inspecting Claims Payloads
Inspect authentication tokens to check custom properties, user permissions, subscription status, and tenant identifiers, verifying backend role mapping configurations during local dev runs. This ensures roles map correctly to database parameters, helping developers debug user flows and resolve access bugs without manual logs.
How It Works
Input Encoded JWT
Paste your encoded token (consisting of Header, Payload, and Signature blocks separated by periods) into the workspace. The tool validates the format, parses periods, and prepares the decoding buffers to check strings.
Base64URL Block Splitting
The decoder splits the input into three segments and applies simple decoding to translate values into readable text strings, handling character sets automatically.
Format Signature Validation
The validator checks date claims (exp, iat, nbf), formats epochs into localized date strings, and compiles statistics on token validity. It calculates time differences relative to your browser clock, validating dates.
Render Interactive JSON
View details in the color-coded editor tabs. Inspect details in the tree view, search claim tags, and copy parameters. All processing runs locally inside the browser sandbox, keeping token information private and secure.
Frequently Asked Questions
A JSON Web Token (JWT) is a secure, standard way to share information between two systems. It looks like a long string of letters and numbers split into three parts by dots. The first part is the header, which says how the key is signed. The middle part is the payload, which holds the actual data (like user profiles or account permission details). The final part is the signature, which ensures the token has not been modified.
This tool is a client-side decoder designed to inspect token headers and claims. It parses signature blocks structurally but does not verify signature signatures, which requires your signing key or public keys. It enables quick payload checks, helping you inspect claims layouts easily without loading private keys into browsers, protecting keys.
The decoder reads the exp (expiration) integer claim, converts it from a Unix timestamp (seconds since epoch) to local date formats, and compares it to the system clock to verify if the token is valid or expired. It evaluates timezone offsets to ensure expiration warnings map correctly to local systems, avoiding timezone errors.
Public claims are standard fields registered in the IANA JSON Web Token Claims registry. These include sub (subject identifier), iss (token issuer), aud (audience client), exp (expiration time), iat (issued at time), and jti (JWT ID). These claims identify who issued the token, who it is for, and when it is valid.
All token parsing and decoding run locally in your browser memory sandbox. No data or token information is sent to external servers, ensuring your access tokens and user claims remain private. This protects developers from leaks of session variables, security tokens, or API credentials, guaranteeing full safety.
Custom claims are custom data fields that you define for your app. For example, you can include properties like `isPremiumSubscriber: true` or `preferredLanguage: 'en'`. Our decoder shows these custom properties clearly in the JSON viewer, helping you verify that your backend servers are attaching the correct details to user keys.
A JWT is encoded using Base64URL encoding so that it can be easily sent over HTTP headers or URLs without losing characters. The dots separate the header, the payload data, and the cryptographic signature. When you decode each part, the first two reveal structured JSON text, while the third part is a binary string used for verifying that the text has not been edited or tampered with.
No, this tool is designed for decoding and inspecting tokens. Creating or signing tokens requires a private cryptographic key, which should never be handled on a public website. To keep your keys safe, you should only sign tokens on your private backend servers.
An Access Token is used to authorize requests to an API, telling the server what permissions the client has. An ID Token is used to carry information about the logged-in user (like their name and profile picture) to the frontend application so the UI can display a personalized welcome screen. Both can be decoded using our tool to view their contents.
The 'iat' field stands for 'Issued At'. It tells you the exact time (as a Unix epoch timestamp) when the token was created. This is useful for checking how old a token is or validating that a token wasn't issued in the future due to clock synchronization problems on servers.