JWT Decoder – Decode & Verify JSON Web Tokens Online Free

Q: Is the JWT decoder free?

Yes, completely free. There are no limits, no accounts, and no charges. Decode as many tokens as you need.

Q: Does this tool verify the JWT signature?

No. This tool decodes and displays the header and payload of a JWT, but it does not verify the signature against a secret or public key, since that would require the signing key. It's meant for inspecting token contents, not validating authenticity.

Q: Is my token sent to a server?

No. All decoding happens entirely in your browser using JavaScript. Your token, and any sensitive data inside it, never leaves your device.

Q: What is a JWT?

A JSON Web Token (JWT) is a compact, URL-safe token format used to represent claims between two parties. It consists of three Base64url-encoded parts separated by dots: a header, a payload, and a signature.

Q: Why does my token show an error?

A JWT must have exactly three Base64url-encoded segments separated by periods. If a segment is missing, truncated, or contains invalid characters, the token cannot be parsed and the tool will show an error.

Q: Can I decode expired tokens?

Yes. The decoder will still show the header and payload of an expired token, and will flag the exp claim so you can see exactly when it expired.

// Features Why Use I7 Pixel's Free JWT Decoder?

Whether you're debugging an auth flow, inspecting an access token, or double-checking an API integration, you need to see inside a JWT fast — without pasting sensitive tokens into a third-party server. I7 Pixel's decoder does it all locally, in your browser.

🔓

Instant Decoding

Paste any JWT and see the decoded header and payload appear immediately — no button click, no delay, no page reload.

🧩

Header, Payload & Signature

All three segments of the token are split out and color-coded, so you can see exactly what each part contains at a glance.

⏱️

Human-Readable Timestamps

Standard claims like exp (expiry) and iat (issued at) are automatically converted from Unix time into readable dates.

🛡️

Algorithm Detection

Instantly see which signing algorithm the token declares — HS256, RS256, ES256, or others — right from the header.

📋

One-Click Copy

Copy the decoded header JSON or payload JSON to your clipboard instantly for use in logs, tickets, or documentation.

⚠️

Clear Error Messages

Malformed or truncated tokens are flagged immediately with a plain-language explanation instead of a cryptic error.

🌗

Light & Dark Mode

Switch themes to match your editor or IDE setup, so the decoded output is easy on the eyes during long debugging sessions.

🔒

100% Private — No Upload

Decoding runs entirely in your browser using JavaScript. Your token, and every claim inside it, never touches a server.

🆓

Free Forever, No Signup

No account, no rate-limited API key, no install. Open the page, paste your token, and read the claims in seconds.

// Guide How to Decode a JWT Online — Step by Step

From a raw token string to readable claims in four quick steps.

1

Paste Your Token

Copy your JSON Web Token and paste it into the input box, or use a sample token to see how the tool works.

2

Decode Instantly

The tool automatically splits the token into header, payload, and signature and decodes each part in real time.

3

Inspect the Claims

Review the algorithm, token type, payload claims, and expiry or issued-at timestamps shown in human-readable form.

4

Copy What You Need

Use the copy buttons to grab the decoded header or payload JSON for debugging, logs, or documentation.

// Deep Dive Understanding JWTs — Structure, Claims & Security

JWTs show up everywhere in modern authentication — API access tokens, single sign-on, session identifiers. Knowing what's actually inside one helps you debug faster and spot problems before they become incidents.

🧱

The Three Parts of a JWT

A JSON Web Token is three Base64url-encoded segments joined by dots: header.payload.signature. The header typically declares the token type and signing algorithm. The payload carries the claims — the actual data, like a user ID, roles, or an expiry time. The signature is computed by signing the header and payload with a secret or private key, and it's what a server checks to confirm the token hasn't been tampered with.

🔍

Decoding vs Verifying — Not the Same Thing

Decoding a JWT just reverses the Base64url encoding to reveal the header and payload as readable JSON — anyone can do this with no key at all. Verifying a JWT is different: it means recomputing the signature with the correct secret or public key and checking it matches, which proves the token is authentic and untampered. This tool decodes tokens for inspection; it does not verify signatures, since that requires a key this tool never has.

🚫

Never Trust an Unverified Token

Because the payload is just Base64url-encoded and not encrypted, anyone who intercepts a JWT can read its claims — and anyone can craft a fake token with whatever claims they like. A server must always verify the signature server-side before trusting anything in the payload. Decoding is for humans debugging; verification is what keeps a system secure.

// Reference Common JWT Claims & What They Mean

Quick guide to the registered claim names you'll most often see in a decoded payload.

Claim	Name	What it Represents
exp Popular	Expiration Time	Unix timestamp after which the token must be rejected as invalid
iat Popular	Issued At	Unix timestamp of when the token was created
nbf	Not Before	Unix timestamp before which the token must not be accepted
sub Popular	Subject	The principal the token is about, usually a user or account ID
iss	Issuer	Identifies the party that issued the token (e.g. an auth server)
aud	Audience	Identifies the intended recipient(s) of the token
alg Popular	Algorithm (header)	The signing algorithm used, such as HS256, RS256, or ES256

// Use Cases Who Needs a JWT Decoder?

Anyone working with token-based authentication runs into a JWT they need to inspect sooner or later — this tool covers every common scenario.

🧑‍💻

Backend Developers

Quickly inspect access tokens and ID tokens while debugging an authentication flow or API integration.

🔐

Security Engineers

Audit token contents for over-broad scopes, missing expiry claims, or unexpected signing algorithms.

📱

Mobile App Developers

Check what claims a token actually carries when a login or session issue only shows up on-device.

🧪

QA & Test Engineers

Verify a test environment is issuing tokens with the correct claims, roles, and expiry before signing off a build.

🎓

Students Learning Auth

See exactly what's inside a real JWT while learning how OAuth, OpenID Connect, or session tokens actually work.

🛠️

DevOps & SRE

Quickly check an expired-token error report by decoding the exp claim without writing a throwaway script.

// FAQ Frequently Asked Questions

Answers to the most common questions about decoding JWTs with this tool.

Yes, completely free. There are no limits, no accounts, and no charges. Decode as many tokens as you need.

No. This tool decodes and displays the header and payload of a JWT, but it does not verify the signature against a secret or public key, since that would require the signing key. It's meant for inspecting token contents, not validating authenticity.

No. All decoding happens entirely in your browser using JavaScript. Your token, and any sensitive data inside it, never leaves your device.

A JSON Web Token (JWT) is a compact, URL-safe token format used to represent claims between two parties. It consists of three Base64url-encoded parts separated by dots: a header, a payload, and a signature.

A JWT must have exactly three Base64url-encoded segments separated by periods. If a segment is missing, truncated, or contains invalid characters, the token cannot be parsed and the tool will show an error.

Yes. The decoder will still show the header and payload of an expired token, and will flag the exp claim so you can see exactly when it expired.

// Reviews User Ratings & Feedback

Tried the tool? Leave a quick rating and help others find it.

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