JWT Inspector Chrome Extension

The JWT Inspector Chrome Extension provides static analysis of JSON Web Tokens (JWTs) by decoding the token into its header and payload and surfacing the key claims that affect security posture. It focuses on conceptual token structure, the relationships between algorithm, issuer, audience, and time-based claims, and it highlights potential misconfigurations for developers and security professionals. It does not rely on external services for decoding, preserving privacy as tokens are inspected locally within the developer environment.
The tool interprets the three parts of a JWT (header, payload, signature), decodes base64url segments, and presents parsed JSON for quick review. It identifies common risk indicators such as expired (exp), not-before (nbf), issued-at (iat) skew, and mismatches between the declared alg and the key material available to the user. It supports optional verification when public keys or JWKs are supplied, enabling cryptographic checks where feasible, otherwise it provides guidance on what cannot be verified without keys.
Beneficiaries include frontend engineers validating authentication tokens, security engineers auditing token configurations, QA analysts reproducing production-like scenarios, and compliance teams confirming standard claims are present. The tool differentiates itself by delivering offline decoding, explicit risk flags, and the ability to attach known keys for optional verification, all without transmitting token data externally. Core features include token parsing, claim extraction, time interpretation, risk flags, and optional signature verification with user-supplied keys; it supports multiple tokens in one session for rapid comparison.