JWT Decoder

Free JWT Decoder that works offline

Inspect the header and payload of a JSON Web Token without transmitting it to a remote debugger. The decoder supports Base64URL segments, formats the resulting JSON and highlights the expiration time when an exp claim is present.

What this jwt decoder does

A typical JWT has header, payload and signature segments separated by dots. The first two segments are encoded rather than encrypted, so their claims can be read without a key. Reading a token does not prove that it is authentic: only signature verification with the expected algorithm and key can establish trust.

How to use the JWT Decoder

1. Paste a three-part JWT into the token field.
2. Select Decode token to parse the header and payload.
3. Review algorithm metadata and claims such as iss, aud, sub, iat and exp.
4. Copy either JSON section, but do not treat the result as signature verification.

Common uses

• Debugging authentication integrations and API requests
• Checking claim names, audiences and expiration times
• Formatting token payloads for local development
• Teaching how JWT encoding differs from encryption and verification

Private processing and offline access

This tool does not submit your input to a conversion server. Processing takes place inside the browser using local JavaScript and standard Web APIs. After the PWA has been installed or cached, the page and its core features remain available without an internet connection. Closing or clearing the page removes unsaved input; the tool does not create an account or cloud history.

Tips for accurate results

• Treat bearer tokens like passwords even though their payload can be decoded.
• Validate issuer, audience, time claims, algorithm and signature on the server.
• An expired label is based on the current device clock and the numeric exp claim.

Frequently asked questions