🔑

JWT Decoder — Decode JSON Web Tokens Online

textClient-side utility

JSON Web Tokens serve as the primary mechanism for transmitting authenticated user claims across modern web applications, microservices, and mobile backends. When an authorized request fails unexpectedly with an authentication error, diagnosing the problem requires reading the token's internal claims to inspect expiration timestamps, user identifiers, and granted permission scopes. Reading raw, dot-separated tokens manually is impractical because the segments are Base64URL-encoded strings. This JWT decoder parses the token into its constituent header, payload, and signature sections, presenting the decoded claims in formatted JSON. Because the decoding logic runs entirely in your browser using client-side JavaScript, your token is not sent to a server, allowing you to debug application credentials privately on your device.

✓ 100% In-Browser Execution✓ Free & No Usage Cap✓ Zero Server Data Storage

🔑 JWT Decoder — Decode JSON Web Tokens

Decode JWT tokens into readable JSON header and payload. No signature verification — just decode. Free, private, runs 100% in your browser.

JWT

📖How to Use This Tool

What is a JWT Decoder?

A JSON Web Token (JWT) is an open standard format defined in RFC 7519 for securely sharing claims between two parties. A standard token consists of three distinct segments delimited by periods: a JOSE header indicating the algorithm, a payload containing application claims, and a digital signature verifying authenticity.

The header and payload are compact, Base64URL-encoded JSON objects. Anyone holding the token can decode and view these segments. Decoding simply unpacks the encoded claims into human-readable JSON so you can inspect expiration dates, scopes, and user identifiers.

How to use it

Paste your encoded token string into the token input box.
The tool parses the string automatically, splitting it into header, payload, and signature sections.
Review the decoded header to check the signing algorithm, and inspect the payload to view token claims.
Note that decoding reveals claims but does not verify the signature — always validate tokens on your own server.

Why use this over alternatives

Many web-based token decoders transmit your credentials across the internet to remote servers for analysis. This tool decodes tokens entirely in your browser using local JavaScript routines. Your credentials and claims are not sent to a server, keeping your session tokens and development data private.

📚 Deep-Dive Architecture Guide

JWT Security in 2026: Safe Authentication & Common Vulnerabilities

Preventing algorithm confusion attacks, none-alg exploits, secure token rotation, and best practices for stateless sessions.

Read Architecture Guide →

🔗Related Tools in this Category

View all text tools →

🔖

Meta Tags Generator — Open Graph & Twitter Card

Optimizing web pages for search engines and social platforms requires configuring proper HTML meta tags in your document head. When articles, landing pages, or blog posts lack standardized Open Graph and Twitter Card tags, social networks like Facebook, LinkedIn, and X generate incomplete link previews with missing headlines, blank descriptions, or distorted thumbnail images. Writing these duplicate tags manually for every page is tedious, and a minor syntax mistake can degrade social engagement and search visibility. This meta tags generator streamlines the process by creating search engine optimization, Open Graph, and Twitter Card tags right inside your browser. Simply input your page title, URL, description, and social share image to generate ready-to-use HTML markup.

📊

Readability Score — Flesch Reading Ease Checker

Content writers, marketers, educators, and technical authors often struggle to gauge whether their prose matches their target audience's comprehension level. Writing that includes overly lengthy sentences, dense clauses, and polysyllabic vocabulary can alienate general readers, reduce conversion rates on landing pages, and lead to misunderstandings in user documentation. Manually counting syllables and sentence structures to evaluate clarity is impractical during drafting. This readability analyzer calculates the Flesch Reading Ease score of your text directly inside your browser. By examining word counts, sentence lengths, and syllable density, it produces a clear reading ease score alongside an estimated education level ranging from elementary school grades through college and graduate comprehension.

🎨

Color Picker — Hex, RGB, HSL Converter

Translating a color choice between design software and web stylesheets frequently causes unnecessary friction. Graphic artists often work with visual color swatches or HSL adjustments, while web developers routinely require six-digit hexadecimal codes or RGB integer triples for CSS rules. Manually converting between these color representations requires tedious math or launching heavy graphic design suites. This live color picker simplifies the process by synchronizing color adjustments across models as you work. Select a shade visually or input an existing code, and view matching HEX, RGB, and HSL representations ready to paste into your design system.

🌈

CSS Gradient Generator — Linear & Radial

Create CSS gradients with live preview.

❓Frequently Asked Questions

Q.Does this tool verify my token's signature against an authentication server?

No. This tool only decodes the token's header and payload directly in your browser — it does not verify signatures or communicate with external authentication providers. Decoding reveals the claims inside; signature validation must happen on your own backend.

Q.Is it safe to paste authentication tokens into this decoder?

The decoding logic runs entirely in your browser using client-side JavaScript, so your token is not sent to a server. However, active production tokens should always be handled with caution. It is good practice to test with expired tokens, sandbox credentials, or staging tokens whenever possible.

Q.What do standard claims like exp, iat, and sub represent?

These are registered claim names defined by the JWT specification. The exp claim indicates the expiration timestamp, iat denotes the issued-at timestamp in Unix time, and sub represents the subject or user identifier. Mismatched or past expiration timestamps are the most frequent cause of authorization rejections.

Q.Why does the tool report that my token is malformed?

A valid token must contain three distinct Base64URL-encoded strings separated by two period characters. Malformed errors typically happen when tokens are accidentally truncated, contain leading spaces or line breaks from copying, or include quotation marks and bearer prefixes from authorization headers. ---

Explore More Developer Utilities

Browse our full suite of 157 browser-based tools, formatters, converters, and guides.

Read Guides & Blog →

📬 Get new tools first

One short email when we launch a new tool. Once or twice a month, no spam. Unsubscribe anytime.

By subscribing you agree to receive emails from Daily Toolbox. See our Privacy Policy.