A JSON Web Token is a compact, URL-safe way to carry JSON claims between parties, usually signed so a server can verify integrity and authenticity.

How do I decode a JWT?

Paste the token above. This tool Base64URL-decodes the header and payload and shows them as JSON.

What are the header, payload and signature?

The header describes the token type and algorithm. The payload holds claims. The signature protects the first two parts when verified with the correct key.

Can I decode a JWT without the secret key?

Yes. Header and payload are encoded, not encrypted, in standard signed JWTs. The secret is required to verify—not to read—those sections.

Is it safe to paste a JWT into an online tool?

This decoder works offline in your browser, but tokens can grant access. Prefer non-production samples, rotate anything sensitive, and never paste long-lived secrets you cannot revoke.

A free online tool that inspects JWT header and payload data for debugging and learning.

How does the JWT Decoder work?

It splits the token on dots, Base64URL-decodes the first two parts, parses JSON, and surfaces warnings such as expiry—without verifying the signature.

How do I use the JWT Decoder?

Paste a JWT, review header and payload panels, and read the safety warnings before you act on the claims.

Is this JWT Decoder free to use?

Yes. It is free with no sign-up.

Can I use the JWT Decoder on mobile?

Yes. It works in mobile browsers for on-the-go debugging.

All free tools

Free tool

Security

JWT Decoder

Paste a JWT to inspect its header and payload in your browser. Built for debugging authentication—not for verifying production signatures.

Runs in your browser — your data stays on your device

Free tool

JWT

Decoding runs in your browser. Never paste production secrets or live access tokens you cannot rotate.

This tool does not verify signatures. Decoding does not prove the token is authentic.

Has signature segment: Yes

Header

{
  "alg": "HS256",
  "typ": "JWT"
}

Payload

{
  "sub": "1234567890",
  "name": "Binary Tech",
  "iat": 1516239022,
  "exp": 1916239022
}

Signature (raw): signature-example

JSON Web Tokens carry claims that web applications and APIs trust after signature checks. This free JWT decoder splits header, payload, and signature so JavaScript developers and cybersecurity students can debug JWT authentication during labs and security testing. Decoding never proves a token is valid—you still need the signing secret or public key on the server.

How to use the JWT Decoder

1
Paste a three-part JWT (you may include or omit a Bearer prefix).
2
Read the pretty-printed header and payload, plus any expiry warnings.
3
Use the output to debug claims—then verify signatures in your own backend, not here.

Why decoding JWTs is a classroom essential

Beginners paste tokens into logs without understanding alg, exp, or sub. API developers who can read payloads fix broken auth faster. Cybersecurity students learn that Base64URL clarity is not authenticity. This tool keeps inspection local so you can practise without shipping tokens to a third-party SaaS.

JWT structure example

A typical JWT looks like header.payload.signature. Decode the sample token on this page to see an alg/HS256-style header and claims such as sub, name, and iat. The signature segment is shown raw because verification requires a secret this demo never asks for.

Guides and next steps

Privacy note

JWT decoding runs in your browser. We do not upload tokens. Avoid pasting irreplaceable production credentials.

Frequently asked questions

Explore more

Related free tools

More password, hash, JWT, and header checkers for secure configuration practice.

View all tools

Developer

Base64 Encoder/Decoder

Free online Base64 encoder/decoder for JavaScript, API, and web developers. Encode or decode UTF-8 text locally in your browser—no install required.

Open tool

Security

Hash Generator

Free online hash generator for cybersecurity and programming students. Create MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes locally in your browser.

Open tool

Security

Password Strength Checker

Free password strength checker for cybersecurity students and website owners. Estimate strength locally in your browser—nothing is uploaded.

Open tool

Developer

URL Encoder/Decoder

Free online URL encoder/decoder for web and API developers. Percent-encode query text or decode %20 sequences locally without installing software.

Open tool

Developer

JSON Formatter

Free online JSON formatter for JavaScript and frontend developers. Pretty-print API responses with 2- or 4-space indent locally in your browser.

Open tool

Developer

JSON Validator

Free online JSON validator for JavaScript and frontend developers. Paste API responses or config files to check syntax and approximate error location—no install.

Open tool

View all free tools

Ready to go beyond free tools?

Live mentor-led courses turn calculator practice into real networking and IT skill.

View recommended course All courses

JWT Decoder

How to use the JWT Decoder

Why decoding JWTs is a classroom essential

JWT structure example

Guides and next steps

Frequently asked questions

What is a JWT?

How do I decode a JWT?

What are the header, payload and signature?

Can I decode a JWT without the secret key?

Is it safe to paste a JWT into an online tool?

What is JWT Decoder?

How does the JWT Decoder work?

How do I use the JWT Decoder?

Is this JWT Decoder free to use?

Can I use the JWT Decoder on mobile?

Related free tools

Base64 Encoder/Decoder

Hash Generator

Password Strength Checker

URL Encoder/Decoder

JSON Formatter

JSON Validator

Ready to go beyond free tools?