JWT Decoder Online Free – Decode & Inspect JSON Web Tokens

🎫 ➜ 🔍

JWT Decoder Online Free

Paste any JSON Web Token and instantly see its header, payload claims and signature — with human-readable iat/exp timestamps, a live expired/still-valid status, and security flags for dangerous token shapes. Decoding happens in your browser — tokens never leave your device.

✓ Claims Viewer · ✓ Expiry Checker · ✓ alg:none Detection · ✓ 100% Private

🔍 JWT Token Inspector

🔧 JS ⏳ · Input — · Decode — · Engine ⏳

Paste your JWT

🧩 Token Anatomy

blue header  green payload  amber signature

📋 Header

📦 Payload Claims

Raw payload JSON

✍️ Signature

The signature cannot be verified without the secret key — this decoder reads, it does not validate. Verification happens on your server.

How to Decode a JWT — 3 Easy Steps

1️⃣

Paste the Token

Drop in the full three-part JWT — with or without a "Bearer " prefix. Cleaning is automatic.

2️⃣

Read the Claims

Header, payload, signature and every claim appear instantly — timestamps shown as real dates.

3️⃣

Check Status

See live expired/still-valid status and security flags, then copy the claims JSON for your code.

Why Use This JWT Parser?

📦

Full Claim View

Every payload claim unpacked with raw JSON beside it — sub, roles, custom fields, everything.

⏰

Readable Timestamps

iat, exp and nbf become real dates with a live expired or still-valid verdict.

🚩

Security Flags

Spots the dangerous alg:none pattern, missing signature, and missing expiration instantly.

🧩

Token Anatomy

The three parts color-coded so you can see exactly how a JWT is assembled.

🔒

100% Private

Tokens stay in your browser — never sent, stored, or logged. Safe for real tokens from your dev environment.

⚡

Instant & Offline

Pure JavaScript decoding on every keystroke — works with no internet at all.

Popular Use Cases

• 🐛 Debug why an API rejected your token — inspect the actual claims sent
• ⏰ Check whether a token is expired or when it will expire
• 🔍 See exactly what data your authentication server puts in tokens
• 🎓 Learn JWT structure by dissecting real examples
• 🚩 Audit tokens for alg:none and missing-expiry red flags
• 🧪 Verify your own generated tokens carry the right claims

Pro Tips for Reading JWTs

• Three parts, two dots: header.payload.signature. A token with only two parts is unsigned (alg none) — treat with suspicion unless you expected it.
• exp is seconds, not milliseconds: if your token's expiry date reads as "Jan 1970", someone fed milliseconds into the claim — a classic integration bug this decoder makes obvious.
• Decoding ≠ verifying: anyone can read a JWT's payload. Only your server, holding the secret, can prove the signature is genuine. Never trust decoded claims until the server verifies them.
• Bearer prefix: tokens often arrive as "Authorization: Bearer eyJ..." — the cleaner strips the prefix so a raw header paste just works.
• Round trip: copy claims from here, edit them in our JWT Encoder, and generate a fresh signed token.

Frequently Asked Questions

Paste the token above — the header, payload and signature split apart instantly with every claim readable. No account, no upload; decoding is pure JavaScript in your browser.

Yes — because a JWT isn't encrypted, only signed. Anyone can read the header and payload; the secret is only needed to verify the signature. That's why you should never put confidential data in JWT claims.

The payload contains an exp claim (Unix seconds). This decoder converts it to a real date and shows a live expired or still-valid badge, comparing against your device's current time.

A token whose header says "alg":"none" claims to have no signature at all. Historically, some libraries accepted such tokens blindly — letting anyone forge admin claims. Servers must reject them; this decoder flags the shape so you can spot it during debugging or review.

The exp claim expects Unix seconds, but someone supplied milliseconds — dividing by 1000 shifts the date to January 1970. If you see this, fix the token generator; the decoder surfaces the mistake instantly.

No — and no browser-only tool honestly can, because verification requires the secret key, which should never be shared with a website. This decoder reads and explains the token; your server performs the cryptographic verification.

This page has no backend — tokens are decoded by JavaScript in your browser and never transmitted or stored. Still, as universal hygiene, prefer pasting test tokens anywhere online and keep production tokens in your own tooling.

Copy the claims JSON here, switch to our JWT Encoder, paste into the payload box, set your secret, and generate a freshly signed token. The two tools work as a pair.