JWT Claims Builder

Build a JWT payload

The payload of a JSON Web Token carries its claims, the pieces of information it asserts, such as who issued it, who it identifies, and when it expires. This builder assembles a well-formed payload from the standard registered claims defined by the JWT specification: issuer, subject, audience, issued-at, not-before and expiry, and lets you add any custom claims your application needs. It automatically sets the issued-at and not-before timestamps to now and computes the expiry from the minutes you specify.

Timestamps use Unix epoch seconds, as the standard requires, and custom values that look like numbers or booleans are typed accordingly.

Claims and token design

Including an expiry claim is important so tokens do not remain valid indefinitely, and the issuer and audience claims let a recipient verify that a token was meant for it and came from a trusted source. Keeping the payload small matters because the token is sent with every request, and remember that the payload is only base64-encoded, not encrypted, so it must never contain secrets or sensitive personal data.

This tool builds the payload only; signing it with a secret or key to produce a complete token is a separate step done securely on the server. All processing happens locally in your browser.

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