# JWT Decoder

> Free, secure client-side JWT decoder. Decode header and payload, inspect claims, expiry, issuer, and timestamps. All processing happens in your browser.

- **Category:** Developer
- **URL:** https://www.teafun.cyou/tools/jwt-decoder/
- **Privacy:** Runs entirely in your browser — no uploads, no account, no tracking.
- **Also known as:** jwt token, bearer token, claims decoder, jwt parser
- **Related tools:** [JSON Formatter & Validator](https://www.teafun.cyou/tools/json-formatter/), [Base64 Encoder / Decoder](https://www.teafun.cyou/tools/base64-tool/), [HTTP Security Headers Checker](https://www.teafun.cyou/tools/http-headers-checker/)
- **Tags:** Data, Security, Text

## About

Decode JWT headers and payloads locally in your browser. Inspect claims, expiry, issuer, and timestamps without sending tokens anywhere.

## How to Use the JWT Decoder

Paste the full token (three dot-separated segments) into the input. The tool splits at the dots, Base64URL-decodes each segment, and renders the header and payload as formatted JSON. Numeric claims like `iat`, `nbf`, and `exp` (Unix seconds since 1970) are converted to ISO-8601 dates alongside the raw value. The status banner reports expired (`now > exp`), not-yet-valid (`now < nbf`), or active. If decoding fails, the error pinpoints which segment was malformed — usually a token truncated by a copy-paste, a Base64URL string missing characters, or accidentally pasting an opaque session ID instead of a JWT. Use Copy to grab the JSON of either segment for further inspection in `jq`, Postman, or your IDE. The signature segment is shown raw — verification is intentionally out of scope.

## Why JWT Inspection Matters

When auth breaks, the first inspection step is always the token: which claims are present, has it expired, does `aud` match the API expecting it, is the `iss` the right authorisation server, did the client request the right `scope`. Without a local decoder, developers paste production tokens into random online sites — every paste is a potential credential leak to whoever owns that site's logs, analytics, or backend. Local Base64URL decoding stops the leak. Beyond debugging, JWT literacy matters for security review: spotting an `alg: none` token, noticing an `exp` that is years in the future, or catching an unexpected role claim in the payload all take seconds with a decoder and minutes without. JWTs are bearer tokens — possession is authorisation. Treating them with care during inspection is the same hygiene as treating production database credentials with care.

_SEO title: JWT Decoder – Privacy-First Token Inspector | TeaFun_

## FAQ

### Does this verify the JWT signature?

No. This page only decodes the header and payload locally. It does not validate signatures or trust the token.

### Why use this instead of jwt.io?

TeaFun emphasises privacy-first decoding. Your token stays in your browser and is never uploaded for processing.

### What timestamps are shown?

If present, exp, iat, and nbf are converted from Unix timestamps into readable ISO dates and local time, so you can see exactly when a token was issued, expires, or becomes valid.