JWT Decoder Online —
jwtdecode vs jwt.io
Both tools decode JWT tokens in-browser. The difference is in analytics, secret-key handling, UI complexity, and account requirements. Here's an honest look at each.
jwtdecode — quick verdict
- ✓ Zero analytics — no scripts phone home
- ✓ Zero server contact — pure JS in page
- ✓ No login, no account, no cookie banner
- ✓ Expiry detection + human-readable timestamps
- ✓ Works offline after page load
- – No signature verification (by design)
- – No shareable permalink
jwt.io — quick verdict
- ✓ Optional HMAC / RSA / ECDSA signature verify
- ✓ Shareable permalink (premium)
- ✓ Large library directory / docs hub
- – Third-party analytics scripts (Google, Segment)
- – Signature verify requires pasting secret key
- – Account / login for team features
- – More UI surface = slower for simple decode
| Feature | jwtdecode | jwt.io |
|---|---|---|
| Token decoding (header + payload) | yes | yes |
| Runs entirely in-browser (no network) | yes | yes |
| Third-party analytics scripts | none | Google + Segment |
| Account / login required | never | optional (paid features) |
| Expiry status + human timestamps | yes — auto | raw Unix only |
| Algorithm display (alg claim) | yes | yes |
| Signature verification | no (by design) | yes (needs secret) |
| Shareable permalink | no | paid plan |
| Works offline (after page load) | yes | partial — CDN fonts may fail |
| Price | free forever | free / paid plans |
| Storage (localStorage / sessionStorage) | none | session preferences stored |
| JWT library reference / docs | no | yes — extensive |
When to use jwtdecode
You need to quickly inspect a token header and payload without setting up an account, accepting a cookie banner, or worrying about which analytics scripts are active on the page. jwtdecode has zero external scripts — the page loads, decodes, and displays. Nothing phones home.
You're working with tokens from production or staging systems. Even though jwt.io also decodes client-side, its analytics scripts (Google Analytics, Segment) observe your page session. Those scripts can see the URL, timing, and interaction metadata of what you're doing. jwtdecode loads no tracking scripts at all.
You want expiry detection out of the box. jwtdecode automatically reads the
exp, iat, and nbf claims and shows them as human-readable
dates with a clear "expired / valid / not yet active" status. jwt.io shows the raw Unix timestamp
and leaves the math to you.
When jwt.io is the better choice
You need signature verification. jwt.io lets you paste an HMAC secret or RSA public key and verify the token signature in-browser. jwtdecode deliberately excludes this — decoding and verifying are different operations, and pasting signing secrets into browser tools is a security anti-pattern we don't want to encourage.
You want the JWT library directory. jwt.io maintains a comprehensive, community-maintained list of JWT libraries across every major language. That reference is genuinely useful when picking a library for your stack.
You need shareable links. jwt.io's paid plans let you generate a permalink for a decoded token (useful in team review or bug reports). jwtdecode has no shareable links.
A note on pasting real tokens
JWT payloads commonly contain user IDs, email addresses, roles, tenant IDs, and session metadata. Decoding a token in a browser tool — even a browser-only one — should be done with awareness:
jwtdecode: no data is transmitted anywhere. The token is processed by JavaScript in the page, displayed, and discarded when you close the tab. No localStorage, no sessionStorage, no analytics.
jwt.io: decoding is also client-side. The risk is the surrounding
analytics infrastructure — scripts that can observe page timing, URL fragments, and interactions.
For tokens from production systems, prefer a tool with no third-party scripts, or do it locally
with node -e "console.log(Buffer.from('PAYLOAD', 'base64').toString())".
Frequently asked questions
Does jwtdecode send my token to a server?
No. All decoding happens in your browser using JavaScript's atob() and JSON.parse(). No network request is made for the token data. Refresh the page and it's gone.
Is jwtdecode safer than jwt.io for production tokens?
jwtdecode has zero analytics scripts, so nothing external observes your session while you inspect the token. jwt.io also decodes client-side, but ships Google Analytics and Segment scripts. For the most sensitive tokens, use a local CLI command or a zero-tracking browser tool.
Can I verify a JWT signature with jwtdecode?
No — by design. Signature verification requires a secret key (HMAC) or public key (RSA/EC). We don't implement it because pasting signing keys into browser tools is a bad habit. Use a server-side library (jsonwebtoken, PyJWT, etc.) for signature verification.
Why does jwtdecode show human-readable dates?
JWT timestamps (exp, iat, nbf) are Unix seconds. Converting to an ISO date string manually takes time and is error-prone. jwtdecode converts them automatically and flags whether the token is currently expired, valid, or not-yet-active at page load time.
Is jwt.io free?
The core debugger at jwt.io is free. Shareable permalink and team collaboration features require a paid plan. jwtdecode is free with no paid tier.
Decode a JWT — no account, no tracking
Paste any JWT token and see header, payload, and expiry status instantly. Runs entirely in your browser.
open jwtdecode →