Paste any JWT — header.payload.signature
TRY A SAMPLE:
Ready to inspect
Paste a JWT and click Inspect// parse header, payload, and signature of any jwt
Instantly decode and inspect JSON Web Tokens (JWT) without a secret key. Parse header, payload, and signature — check claims, expiry, and token structure in your browser.
Ready to inspect
Paste a JWT and click InspectCopy any JWT string and paste it into the input box. The token must follow the header.payload.signature format.
Hit the Inspect JWT button or press Ctrl+Enter to decode the token immediately.
Switch between Header, Payload, Signature, and Raw tabs. Timestamps are shown in human-readable format alongside the raw value.
JWT Inspector decodes JSON Web Tokens directly in your browser — no server, no secret key required. It splits the token into its three Base64URL-encoded parts and shows you the algorithm, claims, expiry, and all standard fields in a clean, readable view.
No. Signature verification requires the secret key (for HMAC algorithms like HS256) or the public key (for RSA/ECDSA algorithms like RS256, ES256). This tool only decodes the Base64URL-encoded parts — it cannot confirm whether the signature is valid without that key.
All decoding happens entirely in your browser using JavaScript — no data is ever sent to a server. That said, JWTs may contain sensitive claims (user IDs, roles, emails). For production secrets, use a local tool or your IDE instead.
A JWT with an exp claim in the past is considered expired. The status bar will show a red "EXPIRED" badge. The token structure is still perfectly decodable — expiry only affects whether a server should accept the token.
This inspector decodes any JWT regardless of algorithm — HS256, HS384, HS512, RS256, RS384, RS512, ES256, ES384, ES512, PS256, and even none. The algorithm is shown in the header tab.
iss = issuer, sub = subject, aud = audience, exp = expiration time, nbf = not before, iat = issued at, jti = JWT ID. All timestamp claims are shown in both Unix epoch and human-readable UTC format.
A JWT consists of three Base64URL-encoded segments joined by dots: the header (algorithm + token type), the payload (claims/data), and the signature (HMAC or asymmetric hash of header + payload). The signature lets servers verify authenticity without re-running the logic.
A JWT Inspector is a browser-based tool that decodes JSON Web Tokens (JWTs) and displays their contents in a structured, human-readable format. Rather than staring at three blocks of Base64URL-encoded text, you get a clear breakdown of the algorithm, all claims, timestamps, and the raw signature — without needing any secret keys.
JWTs are the backbone of modern web authentication. Every time you log into a web app that uses OAuth 2.0, OpenID Connect, or API token authentication, there's a good chance a JWT is being passed around. Inspecting these tokens is essential for debugging authentication flows, auditing security, and understanding how a system works.
💡 Looking for premium web development assets? MonsterONE offers unlimited downloads of templates, UI kits, and developer tools — worth checking out.
Every JWT is made up of exactly three parts, separated by dots (.):
typ, usually JWT) and the signing algorithm (alg, e.g. HS256, RS256, ES256). This is Base64URL-encoded.The JWT specification defines several registered claim names that have specific meanings. This inspector highlights all of them:
https://auth.example.com.There are many valid reasons to decode a JWT without verifying its signature:
Not all authentication tokens are JWTs. Opaque tokens (sometimes called bearer tokens or reference tokens) are random strings with no embedded data — you have to make a network request to an authorization server to find out what they mean. JWTs are "self-contained" — their claims are embedded in the token itself, Base64URL-encoded. This makes JWTs faster to validate (no network round-trip) but means sensitive user data is visible to anyone who holds the token, even without the signing key.
When inspecting a JWT, there are several red flags worth checking:
alg: none, meaning no signature is required. This is a critical vulnerability.exp set years in the future create long windows of exposure if compromised.HS256 with a short or guessable secret is brute-forceable. Prefer RS256 or ES256 for public-facing APIs.JWT timestamps (exp, nbf, iat) are Unix epoch integers — seconds since January 1, 1970 UTC. They're not immediately human-readable. This tool automatically converts them to a clear UTC datetime string alongside the raw value, so you can immediately see "expires in 2 hours" or "issued 3 days ago" without reaching for a separate converter.