Next.js 15.5 Ships - Turbopack Production Builds, Node.js Middleware, and Tighter Typescript DX

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Next.js, the React framework from Vercel, has released version 15.5, a release focused on faster production builds, more powerful server-side middleware, and TypeScript improvements. The update is also starting to warn developers about changes coming in Next.js 16.

Turbopack is an incremental, Rust-based bundler built as a replacement for Webpack, and the Next.js team says they use it in production on Vercel applications. Turbopack for production builds is the headline item in 15.5. Developers can now opt into production Turbopack builds with a single flag:

next build --turbopack

Vercel's benchmarks show meaningful build-time improvements across a range of project sizes, small to large, with 2x to 5x faster compilation times. The release notes also note that Turbopack built projects serve either similar or smaller amounts of JavaScript and CSS with fewer requests.

Another major change in 15.5 is the stabilization of the Node.js middleware runtime. Middleware can now run with full Node APIs available, opening up patterns that were difficult or impossible in the Edge runtime (for example, using native fs/crypto modules or heavier auth flows). They note that although NodeJS runtime will not be set by default in Next 16, it may be in future versions.

TypeScript users receive a batch of practical improvements aimed at reducing runtime surprises and improving DX. Version 15.5 makes typed routes stable (so link targets are validated at compile time), introduces route export validation and helper types (PageProps, LayoutProps and RouteContext), and adds a next typegen command to generate type artifacts without a full build. These changes are intended to catch navigation and export errors earlier in the developer workflow.

The release also formalizes a shift in how Next.js wants projects to handle linting with the next lint command being deprecated in favor of explicit linter configurations (ESLint or alternatives such as Biome). The deprecation is part of a wider push toward making toolchain choices explicit and decoupling Next.js core from prescriptive defaults. Automatic linting during builds will be removed in Next.js 16.

15.5 includes a number of deprecation warnings aimed at smoothing the jump to Next.js 16. The release will surface compile-time or build warnings for items such as legacyBehavior in next/link, AMP, and a set of next/image behavior. These warnings are intended to give teams time to fix before the next major release.

Community reaction has been generally positive to the updates. Many developers feel it is a solid update, typed routing and removing implicit build-time checks are frequently called out. A comment from the r/nextjs subreddit called 15.5 a very solid update and welcomed typed routes and the next lint’s removal. A user on LinkedIn suggested that in their quick testing they saw 20% time improvements using Turbopack.

Next.js is an open-source React framework created by Vercel that provides an opinionated architecture for building full-stack web applications. It extends React with features such as file-system routing, server-side rendering (SSR), static site generation (SSG), API routes, and built-in performance optimizations.

Related Topics:

• Development
• React
• JavaScript
• Front-end
• Node.js
• Web Development
• TypeScript
• Compilers
• ESLint

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