JWT Decoder

Decode JSON Web Tokens instantly to inspect header algorithms, claims, expiration timestamps, and roles without uploading tokens to a remote server.

How to Use JWT Decoder

Paste your encoded JWT string (e.g. eyJhbGciOi...) into the editor.

Click 'Decode' to inspect the token structure.

Examine the decoded JSON Header and Payload sections side by side.

Verify issued-at (iat) and expiration (exp) timestamps.

What This Tool Does

Splits Base64Url-encoded tokens into header, payload, and signature segments. Decodes UTF-8 byte streams and presents formatted JSON claims.

Common Use Cases

Inspecting OAuth2 and OpenID Connect tokens during frontend authentication debugging.

Checking token expiration (exp), audience (aud), and subject (sub) claims.

Debugging user roles and permission scopes passed in backend microservices.

Privacy & Local-First Processing

Decoding is executed 100% locally. Bearer tokens, private claims, and sensitive user emails are never transmitted across the network. Note: client decoding does not verify cryptographic signatures.

Frequently Asked Questions

Does decoding verify the token's cryptographic signature?

No. Client-side decoding extracts and displays readable claims. Signature verification requires your private key or secret and must occur on your backend server.