JWT Decoder
Decode a JSON Web Token to inspect its header and payload claims. Decoding happens locally — your token never leaves the page.
How to use this tool
- 1Paste or type your input above.
- 2The result updates instantly.
- 3Copy the output with one click.
Frequently asked questions
Is this jwt decoder safe to use with sensitive data?+
Yes. Everything is processed locally in your browser using JavaScript — your input is never uploaded or stored on a server.
Is my data private?+
Yes. The tool runs entirely in your browser — nothing you paste or type is uploaded to a server.
Guides & deep dives
JWTs Explained: Header, Payload, Signature and Security Pitfalls
Learn how JSON Web Tokens work — the three parts, signing vs encryption, the alg=none attack, cookie vs localStorage, and expiry claims — with worked examples.
Common JSON Errors and How to Fix Them
Trailing commas, single quotes, unquoted keys, BOM, NaN — learn what breaks JSON and how to fix each error fast with a free online formatter.
Base64 Explained: What It Is and When to Use It
Learn what Base64 encoding is, why it adds 33% overhead, how data URIs work, the base64url variant, and exactly when to encode or decode — with worked examples.
MD5 vs SHA-256: Which Hash Should You Use?
MD5 is broken for security but fine for checksums. SHA-256 is the modern default. Learn the difference, when each applies, and how to hash passwords safely.