JWT Decoder Online — Decode JSON Web Tokens Free
JWT decoder online — decode any JSON Web Token to view header, payload, and claims. Spots expired tokens, exposes algorithm. 100% browser-based, no signup.
PDFFlare's JWT decoder online turns any JSON Web Token into a readable header, payload, and signature in milliseconds. Paste a token and the decoded claims (iss, sub, aud, exp, iat, nbf, jti) appear inline with plain-English explanations, expiration status, and an algorithm warning if the token uses alg: none. Use it as a JWT parser, JWT debugger, or a quick JSON Web Token decoder — no signup, no rate limits, no token leaves your browser.
Working through the same auth or debugging session? Pair this with Base64 Encode / Decode for arbitrary base64url payloads, Hash Generator to compute MD5 / SHA-256 checksums, or UUID Generator to mint jti values for new tokens.
Decoding runs entirely in your browser via atob(), TextDecoder, and JSON.parse(). PDFFlare never sees the token, never logs it, and cannot verify its signature — that requires the issuer's secret or public key, which belongs in your own backend. Use this view JWT claims tool for debugging, learning, and incident response, then verify on a server you trust.
Your token is decoded entirely in your browser using atob() and JSON.parse(). Nothing is sent to a server. PDFFlare cannot verify a JWT's signature without the signing secret or public key — for verification, use your own auth library on a trusted backend.
How to Decode a JWT
Paste your JSON Web Token
Drop the full token (header.payload.signature, three dot-separated parts) into the input box. The decoder runs entirely in your browser — nothing is uploaded.
Inspect the decoded header and payload
The header reveals the signing algorithm (alg) and token type (typ). The payload shows every claim — standard registered claims (iss, sub, aud, exp, iat, nbf, jti) are highlighted with plain-English explanations.
Check expiration and copy any section
A coloured banner shows whether the token is Active, Expires within an hour, or Expired. Use the Copy buttons to grab the header JSON, payload JSON, or raw signature for sharing or further analysis.
When Do You Need a JWT Decoder Online?
Debugging auth flows: Login broken? Refresh-token loop? The first move is to decode JWT online and read what the token actually claims — wrong aud, missing scope, expired exp, or a clock skew between your auth server and your API server. The decoder surfaces these in seconds, before you reach for stack traces.
Inspecting third-party tokens: Integrating with Auth0, Okta, Cognito, Firebase, Supabase, or your own identity provider? Each issuer packs different custom claims into the payload. Use this JWT debugger free to see exactly which claims arrive on your tokens so you wire your middleware to the right field names the first time.
Incident response: When a security alert fires, you often have a captured token and minutes to figure out who issued it, who it's for, and when it expires. Pasting it into a JSON Web Token decoder gives you the answer faster than spinning up your dev environment — and PDFFlare keeps the token in your browser so it never lands in a third-party log.
Learning JWT structure: The fastest way to understand JWTs is to decode a few. Load the sample token, watch how the three base64url parts split, see how the header declares the algorithm, and trace which claims your backend cares about. After a handful of tokens the structure clicks — and PDFFlare's view JWT claims explanations make the standard fields self-documenting.
Why Choose PDFFlare's JWT Decoder?
Header, Payload, and Claims Insights
Decoded JSON for both header and payload, plus a separate Standard Claims block that explains iss, sub, aud, exp, nbf, iat, and jti in plain English.
Expiration & Algorithm Warnings
A traffic-light banner shows Active / Expires within an hour / Expired with the exact ISO timestamp and human-readable relative time. alg: none tokens trigger a clear security warning — never miss them in a code review.
100% Browser-Based
Decoding uses your browser's built-in atob() and JSON.parse(). The token never goes to any server — safe for production access tokens, internal admin sessions, and anything you wouldn't paste into a third-party debugger.
No Signup Required
Free, unlimited, no account, no rate limits, no API keys. Decode JWT online as many times as you need — perfect for debugging in production incidents when every second matters.