JWT Decoder
Decode JSON Web Tokens (JWT) securely in your browser. No data is sent to the server.
About the JWT Decoder
Most JWT decoders online — including the famous one — POST your token to a server before decoding it. That's a problem when the token belongs to a real user session, a production API, or a customer support escalation. This decoder splits the token client-side and base64url-decodes each part inside your browser, so the raw token bytes never touch the network. Header algorithm, payload claims (with iat / exp formatted as human-readable dates), and the raw signature are displayed side by side. Signature verification is intentionally left to your backend — this tool is for inspection, not validation.
What people use it for
- Inspect a production access token without leaking it
- Check the exp claim to debug expired-session issues
- Verify which scopes / roles are present in a customer's token
- Debug Auth0 / Cognito / Clerk / Supabase token contents
- Confirm the alg header matches what your verifier expects
Private by design
Everything you type here is processed inside your browser. Nothing is sent to a server, logged or stored, so it is safe to use with real numbers, drafts and anything you would not paste into a hosted tool.
Try these next
- Base64 Encoder/Decoder Encode and decode Base64 strings in your browser. Handles UTF-8, emoji, and binary safely via TextEncoder. Use for data URIs, JWT inspection, and Basic Auth headers.
- URL Encoder/Decoder Encode and decode URLs and query parameters instantly. Free online URL encoding tool.
- Private JSON Formatter & Validator - Fast, Client-Side Data Tool Free JSON formatter and validator that runs entirely in your browser. Beautify, validate, and pretty-print JSON with no uploads, no sign-up, and no data leaving your device.
- Hash Generator Compute MD5, SHA-1, SHA-256, and SHA-512 hashes from any text or file in your browser using the Web Crypto API. No uploads. Use it to verify file integrity offline.
Browse every tool or read the creator guides.
Questions people ask
How do I decode a JWT token?
Paste your JWT string into the input field. The tool instantly decodes and displays the header, payload, and signature sections.
Is it safe to decode JWTs in a browser?
Yes. This tool runs entirely in your browser. Your JWT is never sent to any server, keeping your tokens secure.
What information is stored in a JWT?
A JWT contains three parts: a header (algorithm and type), a payload (claims like user ID and expiration), and a signature for verification.