JWT Lens

Inspect any JSON Web Token in a tap: color-coded header & payload, human-readable expiry, and local signature verification. 100% on-device — no network, no tracking.

JWT Lens is a fast, private JSON Web Token decoder and verifier for developers — a Safari extension that works entirely on your device.

Tap the toolbar icon, paste a token (or grab the text you've selected on the page), and instantly see:

• Pretty-printed, color-coded Header and Payload • Human-readable timestamps — exp, iat and nbf shown in your local time with relative phrasing ("expires in 59 minutes") • An at-a-glance expiry badge: valid, expired, or not yet valid • Plain-English descriptions of standard claims (iss, sub, aud, and more)

Need to check a signature? JWT Lens verifies HS256/384/512, RS256/384/512, PS256/384/512 and ES256/384/512 using a secret or PEM public key you provide — all computed locally with the system's WebCrypto, never sent anywhere.

Privacy by design: • No network requests — ever • No analytics, no tracking, no accounts • Nothing is stored: tokens and keys live only in the popup while you use it

Whether you're debugging OAuth / OIDC flows, inspecting a bearer token, or learning how JWTs work, JWT Lens keeps it quick, clear, and completely on-device.

Universal app: works in Safari on macOS, iOS and iPadOS.