Is JWT Debugger free?

Yes. Every VersaTools tool is completely free — no account, no watermark, and no sign-up required.

Is my token sent to a server?

No. The token is decoded locally in your browser using standard base64url decoding, so it is never uploaded, stored, or logged anywhere.

Does it verify the signature?

No. Verification requires the issuer's secret (for HMAC) or public key (for RSA/ECDSA), which you should never paste into a website. This tool decodes the token so you can read it, but confirming authenticity must be done server-side.

Is it safe to paste a real token here?

Decoding is local and nothing is transmitted, but a JWT is a credential. As with any secret, avoid pasting live production tokens into tools you do not control, and remember a decoded payload is not proof the token is genuine.

Why does my token fail to decode?

A valid JWT has three dot-separated, base64url-encoded parts. If a segment is truncated, re-encoded, or not valid JSON after decoding, the tool shows a message pointing to the part that failed.

JWT Debugger

Developer Utilities

Decode a JSON Web Token and inspect its header and payload.

Encoded token

Header

{
  "alg": "HS256",
  "typ": "JWT"
}

Payload

{
  "sub": "1234567890",
  "name": "Jane Doe",
  "admin": true,
  "iat": 1700000000,
  "exp": 1900000000
}

Timestamps

iatIssued at:Tue, 14 Nov 2023 22:13:20 GMT
expExpires:Sun, 17 Mar 2030 17:46:40 GMTValid

Signature

sVh7Vghpv9aG3Tq9m0m8kZ2m2m4Qd0oQ4iZ3aXn7d1Y

The signature is shown as-is but not verified. Verifying it requires the issuer's secret or public key, which is never entered here — so this tool only decodes the token, it does not confirm the signature is authentic. Never trust a decoded payload without server-side verification.

Decoded entirely in your browser. Your token is never uploaded or logged.

Tool Overview & Guide

What is JWT Debugger?

JWT Debugger decodes a JSON Web Token and lays out its header, payload, and signature so you can see exactly what a token contains. It pretty-prints the JSON of each section and translates the iat, nbf, and exp timestamps into human-readable dates, flagging whether the token has expired. Decoding happens entirely in your browser — your token is never uploaded — and the signature is shown but not verified, because that requires a secret or key you should never paste into a website.

Technical Specifications & Supported Formats

Processing Engine:Client-side Native JavaScript & WebAssembly

Privacy & Security:100% In-Browser (Zero File Upload)

Supported Formats:All Standard Formats & Code Text

Max File Limit:100 MB

How to use JWT Debugger

3 simple steps to complete your task directly in your browser:

Paste your token
Drop a JWT (it usually starts with eyJ) into the Encoded token box, or click Load sample to try a harmless example token.
Read the header
The Header panel shows the decoded JSON, including the signing algorithm (alg) and token type (typ), pretty-printed for easy scanning.
Inspect the payload
The Payload panel shows every claim in the token — subject, custom fields, roles, and standard registered claims.

Common uses

Inspect the claims inside a token returned by an auth API
Check whether a token has expired and when it was issued
Confirm which algorithm a token was signed with
Debug why a request is rejected by reading the payload roles or scopes
Learn how JWTs are structured into header, payload, and signature
Copy a decoded payload into a bug report or ticket

Why choose VersaTools

100% private

Your files are processed inside your browser and are never uploaded to a server.

Free, no account

No sign-up, no watermark, no paywalled “premium” tier. Just open a tool and use it.

Instant

No upload, no queue, no server round-trip — work starts the moment you drop a file.

Runs in your browser

Built on open web standards. Works on any modern desktop browser, nothing to install.

No upload size caps

Nothing leaves your device, so there’s no server file-size limit — only your machine’s memory.

Yours to keep

Results download straight to your device in clean, standard file formats.