--- title: What Are JWTs? | daily.dev description: A beginner-friendly explainer on JSON Web Tokens (JWTs), covering what they are, why they solve session management problems in distributed systems, their... canonical: https://daily.dev/posts/what-are-jwts--y4dxgg1vx twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: What Are JWTs? | daily.dev og:description: A beginner-friendly explainer on JSON Web Tokens (JWTs), covering what they are, why they solve session management problems in distributed systems, their... og:url: https://daily.dev/posts/what-are-jwts--y4dxgg1vx og:image: https://api.daily.dev/og/posts/y4DxGG1vx.png og:image:alt: What Are JWTs? og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # What Are JWTs? **[Teleport](https://daily.dev/sources/teleport)** · 12 min read · 0 upvotes · 0 comments ## Summary A beginner-friendly explainer on JSON Web Tokens (JWTs), covering what they are, why they solve session management problems in distributed systems, their structure (header, payload, signature), key benefits (security, compactness, flexibility), and common implementation pitfalls such as weak secrets, long expiry times, improper storage, missing validation, and use of the 'none' algorithm exploit. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What are the most common mistakes developers make when implementing JWT authentication? Common JWT implementation mistakes include using weak token secrets that can be brute-forced, setting long expiry times that increase exposure if a token is stolen, using JWTs as session cookies unnecessarily, storing tokens in local storage instead of session storage or encrypted device storage, failing to validate tokens against a JWKS endpoint, and transmitting tokens over HTTP instead of HTTPS. _daily.dev surfaces practical security guidance for developers hardening their authentication flows._ ### What is the 'none algorithm' vulnerability in JWT and how do I protect against it? The none algorithm vulnerability occurs when an attacker alters a JWT's header to set the algorithm to 'none', which can bypass signature verification if the server accepts it, allowing forged tokens to pass as valid. Protection involves explicitly rejecting any token with a none algorithm; many libraries and frameworks already block this by default. _Developers securing token-based auth can track JWT security pitfalls like this via daily.dev._ ### Where should I store a JWT on the client side to keep it secure? JWTs should not be stored in local storage since it is easily accessible to third-party scripts and vulnerable to XSS attacks. Recommended alternatives are session storage, which clears when the browser or tab closes, or encrypted storage on client devices such as mobile and desktop apps. _daily.dev helps developers weighing token storage trade-offs stay grounded in security best practices._ ## Similar posts on daily.dev - [JWT Authentication in Node.js Explained Simply](https://daily.dev/posts/jwt-authentication-in-node-js-explained-simply-spsvcdwti) · Towards Dev · 5 upvotes · 1 comments - [JWT Authentication Without the Confusion](https://daily.dev/posts/jwt-authentication-without-the-confusion-tvh5u1id9) · Medium · 1 upvotes · 0 comments - [How To Use JSON Web Tokens \(JWTs\) in Express.js](https://daily.dev/posts/how-to-use-json-web-tokens-jwts-in-express-js-72ojkkino) · DigitalOcean Community · 7 upvotes · 0 comments - [What are Auth Tokens? Complete Guide to Token-Based Authentication & Implementation](https://daily.dev/posts/what-are-auth-tokens-complete-guide-to-token-based-authentication-implementation-mqxqlegu7) · Security Boulevard · 2 upvotes · 0 comments - [JWT Session 1: Why Modern ASP.NET Core Web APIs Use JWT Instead of Sessions](https://daily.dev/posts/jwt-session-1-why-modern-asp-net-core-web-apis-use-jwt-instead-of-sessions-ibyjum8lw) · C\# Corner · 1 upvotes · 0 comments --- Tags: [#authentication](https://daily.dev/tags/authentication), [#cryptography](https://daily.dev/tags/cryptography), [#authorization](https://daily.dev/tags/authorization), [#web-security](https://daily.dev/tags/web-security), [#jwt](https://daily.dev/tags/jwt) [View this post on daily.dev](https://daily.dev/posts/what-are-jwts--y4dxgg1vx) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"What Are JWTs?","url":"https://daily.dev/posts/what-are-jwts--y4dxgg1vx","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/what-are-jwts--y4dxgg1vx"},"datePublished":"2026-08-23T12:23:03.013Z","dateModified":"2026-08-23T12:53:17.047Z","description":"A beginner-friendly explainer on JSON Web Tokens (JWTs), covering what they are, why they solve session management problems in distributed systems, their...","image":"https://media.daily.dev/image/upload/s--foaA6JGU--/f_auto/v1722860399/public/Placeholder%2004","thumbnailUrl":"https://media.daily.dev/image/upload/s--foaA6JGU--/f_auto/v1722860399/public/Placeholder%2004","isAccessibleForFree":true,"articleSection":"Teleport","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Teleport","logo":"https://media.daily.dev/image/upload/s--Dw-Bbw6O--/c_limit,w_256/f_auto,q_auto/v1787487494/logos/teleport?_a=BAMAMicg0","url":"https://daily.dev/sources/teleport"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/what-are-jwts--y4dxgg1vx","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"authentication,cryptography,authorization,web-security,jwt","timeRequired":"PT12M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Teleport","item":"https://daily.dev/sources/teleport"},{"@type":"ListItem","position":3,"name":"What Are JWTs?"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/what-are-jwts--y4dxgg1vx#faq","mainEntity":[{"@type":"Question","name":"What are the most common mistakes developers make when implementing JWT authentication?","acceptedAnswer":{"@type":"Answer","text":"Common JWT implementation mistakes include using weak token secrets that can be brute-forced, setting long expiry times that increase exposure if a token is stolen, using JWTs as session cookies unnecessarily, storing tokens in local storage instead of session storage or encrypted device storage, failing to validate tokens against a JWKS endpoint, and transmitting tokens over HTTP instead of HTTPS. daily.dev surfaces practical security guidance for developers hardening their authentication flows."}},{"@type":"Question","name":"What is the 'none algorithm' vulnerability in JWT and how do I protect against it?","acceptedAnswer":{"@type":"Answer","text":"The none algorithm vulnerability occurs when an attacker alters a JWT's header to set the algorithm to 'none', which can bypass signature verification if the server accepts it, allowing forged tokens to pass as valid. 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