--- title: adam bien's blog | daily.dev description: zws is a lightweight development web server implemented in a single Java 25 source file, built on top of the JDK's built-in HTTP server. It serves static files... canonical: https://daily.dev/posts/adam-bien-s-blog-mpjb4fu8k twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: adam bien's blog | daily.dev og:description: zws is a lightweight development web server implemented in a single Java 25 source file, built on top of the JDK's built-in HTTP server. It serves static files... og:url: https://daily.dev/posts/adam-bien-s-blog-mpjb4fu8k og:image: https://api.daily.dev/og/posts/mPJB4fu8k.png og:image:alt: adam bien's blog 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. # adam bien's blog **[Adam Bien](https://daily.dev/sources/adam-bien)** · 2 min read · 1 upvotes · 0 comments ## Summary zws is a lightweight development web server implemented in a single Java 25 source file, built on top of the JDK's built-in HTTP server. It serves static files with no-cache headers and supports two key features: live reload via Server-Sent Events and WatchService (injecting a one-liner script into HTML pages that triggers a browser refresh on file changes), and SPA routing fallback that serves index.html for extensionless paths not found on disk. No dependencies, no build step, no WebSockets — just Java 25 and standard web APIs. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I add live reload to a static site without using any JavaScript build tools or WebSockets? A single Java 25 source file called zws can serve this purpose: it watches a directory with the WatchService API and injects a one-line script using Server-Sent Events into every served HTML page, so the browser reloads automatically whenever a file changes. The SSE connection is kept open on a virtual thread, requiring no WebSockets, no client library, and no build step. _Developers wiring up minimal dev tooling can find practical Java setups like this one on daily.dev._ ### How do I serve a single page application with client-side routing from a plain Java HTTP server without a framework? Using the zws tool's --single flag, GET requests for extensionless paths that don't exist on disk are answered with index.html, letting client-side routes like /add work on deep links and page reloads. Requests that include a file extension still return 404, so typos in file paths remain visible instead of being silently swallowed. _Teams evaluating lightweight SPA-serving options can track approaches like this on daily.dev._ ## Similar posts on daily.dev - [foojay – a place for friends of OpenJDK](https://daily.dev/posts/foojay-a-place-for-friends-of-openjdk-fe135kidv) · Foojay.io · 0 upvotes · 0 comments --- Tags: [#webdev](https://daily.dev/tags/webdev), [#java](https://daily.dev/tags/java), [#server-sent-events](https://daily.dev/tags/server-sent-events) [View this post on daily.dev](https://daily.dev/posts/adam-bien-s-blog-mpjb4fu8k) ```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":"adam bien's blog","url":"https://daily.dev/posts/adam-bien-s-blog-mpjb4fu8k","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/adam-bien-s-blog-mpjb4fu8k"},"datePublished":"2026-07-15T06:08:01.344Z","dateModified":"2026-09-14T07:00:33.735Z","description":"zws is a lightweight development web server implemented in a single Java 25 source file, built on top of the JDK's built-in HTTP server. 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