--- title: The new Firebase JS SDK is now GA | daily.dev description: Firebase's version 9 JavaScript SDK is now generally available, introducing a modular, function-based API designed for tree shaking that can cut bundle sizes... canonical: https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: The new Firebase JS SDK is now GA | daily.dev og:description: Firebase's version 9 JavaScript SDK is now generally available, introducing a modular, function-based API designed for tree shaking that can cut bundle sizes... og:url: https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s og:image: https://api.daily.dev/og/posts/FOdHZCW2S.png og:image:alt: The new Firebase JS SDK is now GA 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. # The new Firebase JS SDK is now GA **[Firebase](https://daily.dev/sources/firebase-blog)** · 5 min read · 0 upvotes · 0 comments ## Summary Firebase's version 9 JavaScript SDK is now generally available, introducing a modular, function-based API designed for tree shaking that can cut bundle sizes by up to 80% in some cases. Running npm install firebase now pulls in v9, which is a major release with breaking changes; a compatibility library mirroring the v8 API is provided for gradual migration. The release also introduces Firestore Lite, a REST-based, smaller alternative to full Firestore for one-time reads, and moves away from reliance on the browser's global window object toward ES modules. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What changed in Firebase JS SDK version 9 compared to version 8? Firebase JS SDK v9 replaces the object-oriented API with a modular, function-based approach that supports tree shaking, cutting bundle sizes by up to 80% in some scenarios and 72% in a direct auth example comparison. Running npm install firebase now installs v9 by default. It is a major release with breaking changes, though a compatibility library mirroring the v8 API is bundled to ease migration. _Track SDK migrations like this one on daily.dev before they break a production build._ ### How do I migrate my code to Firebase JS SDK v9 without rewriting everything at once? Use the compatibility library shipped with the version 9 npm package, which mirrors the version 8 API while running on the version 9 library internally, referred to as interop-mode. Only the import path needs to change (e.g. firebase/compat/app instead of firebase/app), letting old and new APIs coexist until the codebase is fully upgraded, at which point the compatibility library can be removed for full tree-shaking benefits. _daily.dev helps developers planning phased SDK upgrades keep track of migration guidance like this._ ### What is Firestore Lite and when should I use it instead of the full Firestore SDK? Firestore Lite is a REST-based Firestore library with a much smaller bundle size, introduced alongside Firebase JS SDK v9. It lacks realtime reads and offline support, making it ideal for pages that only need one-time document reads; it can also be combined with the full Firestore package in the same app where some pages need realtime streams and others don't. _Developers weighing bundle size against realtime features can follow updates like Firestore Lite on daily.dev._ --- Tags: [#webdev](https://daily.dev/tags/webdev), [#javascript](https://daily.dev/tags/javascript), [#firebase](https://daily.dev/tags/firebase), [#firestore](https://daily.dev/tags/firestore) [View this post on daily.dev](https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s) ```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":"The new Firebase JS SDK is now GA","url":"https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s"},"datePublished":"2026-08-23T12:18:06.499Z","dateModified":"2026-08-23T12:32:53.015Z","description":"Firebase's version 9 JavaScript SDK is now generally available, introducing a modular, function-based API designed for tree shaking that can cut bundle sizes...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/7ed721de96163685d26ab7e314be3ebc?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/7ed721de96163685d26ab7e314be3ebc?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Firebase","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":"Firebase","logo":"https://media.daily.dev/image/upload/s--i395oqZH--/f_auto,q_auto/v1787487448/logos/firebase-blog?_a=BAMAMicg0","url":"https://daily.dev/sources/firebase-blog"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"webdev,javascript,firebase,firestore","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Firebase","item":"https://daily.dev/sources/firebase-blog"},{"@type":"ListItem","position":3,"name":"The new Firebase JS SDK is now GA"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/the-new-firebase-js-sdk-is-now-ga-fodhzcw2s#faq","mainEntity":[{"@type":"Question","name":"What changed in Firebase JS SDK version 9 compared to version 8?","acceptedAnswer":{"@type":"Answer","text":"Firebase JS SDK v9 replaces the object-oriented API with a modular, function-based approach that supports tree shaking, cutting bundle sizes by up to 80% in some scenarios and 72% in a direct auth example comparison. 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