JWT Decoder
Decode JWT header and payload in your browser. Inspect claims like alg, iat, and exp without sending tokens to a server.
Why use our JWT Decoder?
Instant Claim Inspection
Paste a token and immediately view header and payload claims like alg, iat, exp, sub, and custom fields.
Safe Local Decoding
Tokens are decoded in your browser only. Nothing is uploaded — ideal when debugging real credentials.
Clear Debugging Context
See structured JSON for header and payload so auth failures are easier to diagnose.
What is a JWT Decoder?
A JWT decoder is a developer tool that parses JSON Web Tokens into readable header and payload JSON. JWTs are compact, URL-safe strings used for authentication and authorization across APIs, single sign-on, and microservices. Each token has three Base64URL-encoded parts separated by dots: header, payload, and signature.
Our free online JWT decoder helps you inspect claims during development and debugging without writing scripts. It does not verify signatures — verification needs your secret or public key in your backend. Use this tool to understand what a token contains, then verify integrity in your application.
What You Can Inspect
- Header:Token type and signing algorithm (HS256, RS256, and more).
- Payload:Standard and custom claims such as sub, iss, aud, iat, and exp.
- Signature:Shown as the third segment; not verified by this decoder.
- Expiry claims:Review time-based claims even when a token is already expired.
- Copy JSON:Copy formatted header or payload for tickets and logs.
- Privacy:100% client-side decoding — tokens never leave your device.
Common Use Cases
Debug Auth Failures
Confirm expiry, audience, and issuer when login or API calls return 401 Unauthorized errors.
OAuth / OIDC Integration
Inspect ID and access token claims while wiring up identity providers and SSO flows.
Algorithm Checks
Verify the header alg matches what your API gateway or resource server expects.
Support & Incidents
Decode customer-provided tokens locally without pasting secrets into untrusted websites.
Learn JWT Claims
Explore how iat, exp, nbf, roles, and custom claims appear in real-world tokens.
SPA Development
Quickly inspect tokens stored in localStorage, sessionStorage, or cookies during frontend work.
How to Use the JWT Decoder
Paste Your JWT
Copy a token in header.payload.signature form and paste it into the input field.
Decode the Token
Click Decode JWT to parse the Base64URL header and payload into formatted JSON.
Review Claims
Inspect algorithm, issued-at, expiry, subject, and any custom application claims.
Copy What You Need
Copy header or payload JSON for debugging notes, support tickets, or test fixtures.
Benefits of Using a JWT Decoder
Faster Auth Debugging
Skip manual Base64 decoding and jq scripts when you only need to read claims quickly.
Fewer Guessing Games
See exactly which claims a failing token contains before changing server config.
Safer Than Random Sites
Local browser decoding reduces the risk of leaking production tokens to third parties.
Works Offline in Browser
Once the page is loaded, decoding does not depend on an API round trip.
Great for Teaching
Show teammates how JWTs are structured with live examples during onboarding.
Completely Free
No signup, no rate limits for typical debugging, and no extension install required.
JWT Debugging Tips
- •Three parts required: A valid JWT has exactly two dots separating header, payload, and signature.
- •Decode ≠ verify: Anyone can read claims; only signature verification proves the token was not tampered with.
- •Check exp and nbf: Many “invalid token” bugs are simply expired or not-yet-valid timestamps.
- •Watch alg carefully: Reject unexpected algorithms in production to avoid algorithm-confusion issues.
- •Avoid logging full tokens: Prefer logging claim summaries; raw JWTs can grant access if leaked.
- •Use HTTPS everywhere: JWTs in transit should always be protected by TLS in real applications.
Start Decoding JWTs Now
Whether you are debugging OAuth callbacks, API gateways, or session cookies, our free JWT decoder gives you instant visibility into header and payload claims. Inspect alg, iat, exp, and custom fields without writing a script.
Scroll up, paste your token, and decode locally in your browser. No registration required, completely free, and your JWT stays 100% private. Trusted by developers who need a fast, private token inspector.
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Frequently Asked Questions
Is my JWT uploaded to a server?
No. Decoding happens entirely in your browser. Your token is never sent to any server, keeping sensitive credentials private.
Does this tool verify JWT signatures?
No. This decoder only parses the Base64URL-encoded header and payload for inspection. Signature verification requires the secret or public key and is not performed here.
What if decoding fails?
Check that the token has exactly three dot-separated parts and that the header and payload are valid Base64URL-encoded JSON.
Can I decode expired tokens?
Yes. Expiry is shown as a claim when present. Decoding works regardless of whether the token has expired.
What is the difference between JWT header and payload?
The header describes metadata such as algorithm and token type. The payload contains claims about the user or session, including standard fields and custom application data.
Is this JWT decoder free?
Yes. It is completely free to use with no registration, downloads, or hidden fees.
Can I decode tokens from Auth0, Firebase, or Cognito?
Yes. Any standard JWT in three-part form can be decoded for inspection, regardless of the identity provider that issued it.
Should I paste production tokens into online tools?
Prefer local-only tools like this one. Even then, avoid sharing production tokens in screenshots, tickets, or chat unless necessary.