Does this tool verify the JWT signature?

No, this tool only decodes the header and payload — it does not verify the signature. Signature verification requires the secret key or public key used to sign the token, which should never be entered into a third-party tool.

Is it safe to paste a JWT here?

Decoding happens entirely in your browser using client-side JavaScript. The token is never sent to any server. However, avoid pasting tokens containing sensitive production secrets into any online tool as a general precaution.

What are the three parts of a JWT?

A JWT has a header, payload, and signature, separated by dots. The header describes the signing algorithm and token type, the payload contains the claims (the actual data), and the signature is used to verify the token has not been tampered with — though this tool does not verify it.

What do the "exp" and "iat" claims mean?

"iat" is the issued-at timestamp — when the token was created. "exp" is the expiration timestamp — when the token stops being valid. Both are Unix timestamps, which this tool converts into human-readable dates automatically.

Why does my JWT show an "Invalid JWT" error?

This usually means the pasted text isn't a valid three-part JWT — a segment may be missing, there could be extra whitespace, or the string isn't properly Base64URL-encoded JSON. Double-check you copied the complete token, including all three dot-separated parts.

Can this tool create or sign a JWT?

No, this is a decoder only. It reads and displays the header and payload of an existing token — it doesn't generate, sign, or verify tokens.

JWT Decoder — Decode JSON Web Tokens Online

Overview

JWT Decoder is a free tool on ToolifHub that decodes a JSON Web Token's header and payload into readable JSON as you type. A JWT is made of three dot-separated parts — header, payload, and signature — commonly used to carry authentication and authorization claims between a client and a server. This tool converts numeric exp (expiration) and iat (issued-at) claims into human-readable dates and clearly flags a token as expired when applicable. In the interest of transparency: this is a decoder, not a verifier — it does not and cannot check the token's signature, and everything runs locally in your browser so the token itself is never sent to a server.

About JWT Decoder

Paste any JSON Web Token (JWT) to instantly decode its header and payload into readable JSON. View expiration (exp) and issued-at (iat) claims as human-readable dates. All decoding happens locally in your browser — the signature is never verified or sent anywhere.

Key Features

Instantly decodes a JWT's header and payload into readable JSON as you type

Converts exp and iat numeric timestamps into human-readable dates

Flags expired tokens with a clear "(expired)" label

One-click copy of the decoded header or payload

100% free with no sign-up or account required

Decodes entirely in your browser — the token is never sent to a server

Benefits

Quickly inspect the claims inside an access or ID token while debugging authentication issues

Instantly see whether a token has expired without writing a script

Understand a third-party API's JWT structure before integrating it

Verify a payload matches what your backend is supposed to be issuing

Keep tokens private since decoding never leaves your browser

How to Use JWT Decoder

Paste your JWT into the input box

The header and payload decode automatically as you type — no button click needed

Review the Issued At and Expires At dates if the token includes exp/iat claims

Check for the red "(expired)" label to see if the token is no longer valid

Copy the header or payload JSON with one click for debugging or documentation

Remember: this tool only decodes — it never verifies the token's signature

Use Cases

Backend Developers

Inspect the claims inside an access token while debugging an authentication flow.

Frontend Developers

Check what data is available in an ID token before building a UI around it.

QA & Testers

Quickly verify a JWT hasn't expired when investigating a failed API request.

API Integrators

Understand a third-party service's JWT structure before writing integration code.

Security-Conscious Developers

Decode and review a token's contents locally without sending it to an external service.

JWT Decoder

Overview

About JWT Decoder

Key Features

Benefits

How to Use JWT Decoder

Use Cases

Backend Developers

Frontend Developers

QA & Testers

API Integrators

Security-Conscious Developers

Frequently Asked Questions

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