--- title: Node.js 27.0.0-alpha.0.0.0 (Alpha) | daily.dev description: Node.js 27.0.0-alpha.0.0.0 ships with V8 upgraded to 15.6.75.13, up from 14.6 in Node.js 26. The update enables new language features by default, including... canonical: https://daily.dev/posts/node-js-27-0-0-alpha-0-0-0-alpha--evmbgjjqp twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Node.js 27.0.0-alpha.0.0.0 (Alpha) | daily.dev og:description: Node.js 27.0.0-alpha.0.0.0 ships with V8 upgraded to 15.6.75.13, up from 14.6 in Node.js 26. The update enables new language features by default, including... og:url: https://daily.dev/posts/node-js-27-0-0-alpha-0-0-0-alpha--evmbgjjqp og:image: https://api.daily.dev/og/posts/eVmbgjJQp.png og:image:alt: Node.js 27.0.0-alpha.0.0.0 (Alpha) 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. # Node.js 27.0.0-alpha.0.0.0 (Alpha) **[Node.js](https://daily.dev/sources/nodejs)** · 34 min read · 2 upvotes · 0 comments ## Summary Node.js 27.0.0-alpha.0.0.0 ships with V8 upgraded to 15.6.75.13, up from 14.6 in Node.js 26. The update enables new language features by default, including Math.sumPrecise(), Iterator.prototype.join() and Iterator.zip(). When --max-old-space-size isn't set, the default heap limit is now half of physical memory, clamped between 256 MB and 4 GB, and Buffer/ArrayBuffer memory now counts toward that limit. v8.serialize(), structuredClone() and postMessage() switch to a new format older Node.js releases can't read. The alpha also bundles dozens of SEMVER-MAJOR changes, like requiring OpenSSL 3+, removing the FIPS provider build, and raising the default HTTP keepAliveTimeout to 65 seconds. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What V8 version does Node.js 27 alpha use and what's new in it? Node.js 27.0.0-alpha.0.0.0 updates V8 to version 15.6.75.13, up from 14.6 in Node.js 26. New default language features include Math.sumPrecise(), Intl.Locale.prototype.variants, Iterator.prototype.join(), Iterator.prototype.includes(), Iterator.zip() and Iterator.zipKeyed(). Experimental features behind flags include import defer and immutable ArrayBuffer. _Developers planning a V8 bump can track Node.js version changes like these on daily.dev._ ### How does Node.js 27 change the default max-old-space-size heap limit? When --max-old-space-size is not set, the default heap size limit becomes half of the physical memory, clamped between 256 MB and 4 GB. Additionally, memory held by Buffer and ArrayBuffer instances now counts toward that heap limit. Applications relying on the old defaults should set --max-old-space-size explicitly to avoid unexpected behavior. _Teams tuning memory limits before a major Node.js upgrade can follow coverage like this on daily.dev._ ### Will structuredClone() output from Node.js 27 be readable by older Node.js versions? No, v8.serialize(), structuredClone() and postMessage() use a new serialization format in Node.js 27 that older Node.js releases cannot read. This also means v8.cachedDataVersionTag() and the compile cache change on every Node.js patch tied to V8, not only on V8 version bumps, which can affect cross-version compatibility and caching setups. _Developers checking cross-version compatibility before upgrading can follow Node.js release details on daily.dev._ ## Similar posts on daily.dev - [Node.js — Node.js 24.15.0 \(LTS\)](https://daily.dev/posts/node-js-node-js-24-15-0-lts--nsrp0vl5j) · Node.js · 107 upvotes · 3 comments - [Node.js 26: Temporal API Enabled by Default, V8 14.6, and a Round of Deprecations](https://daily.dev/posts/node-js-26-temporal-api-enabled-by-default-v8-14-6-and-a-round-of-deprecations-8f8xftnj7) · InfoQ · 5 upvotes · 0 comments - [Node.js — Node.js 26.11.0 \(Current\)](https://daily.dev/posts/node-js-node-js-26-11-0-current--ljtb1vimc) · Node.js · 7 upvotes · 1 comments - [Node.js — Node.js 26.0.0 \(Current\)](https://daily.dev/posts/node-js-node-js-26-0-0-current--xsccfs0nf) · Node.js · 98 upvotes · 0 comments --- Tags: [#javascript](https://daily.dev/tags/javascript), [#nodejs](https://daily.dev/tags/nodejs), [#cryptography](https://daily.dev/tags/cryptography), [#v8](https://daily.dev/tags/v8) [View this post on daily.dev](https://daily.dev/posts/node-js-27-0-0-alpha-0-0-0-alpha--evmbgjjqp) ```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":"Node.js 27.0.0-alpha.0.0.0 (Alpha)","url":"https://daily.dev/posts/node-js-27-0-0-alpha-0-0-0-alpha--evmbgjjqp","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/node-js-27-0-0-alpha-0-0-0-alpha--evmbgjjqp"},"datePublished":"2026-10-29T22:43:34.033Z","dateModified":"2026-10-29T22:51:49.030Z","description":"Node.js 27.0.0-alpha.0.0.0 ships with V8 upgraded to 15.6.75.13, up from 14.6 in Node.js 26. 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