useTypeScriptCli

By default, next build runs the project-local tsc command instead of loading the TypeScript JavaScript compiler API. This supports TypeScript 6 and enables TypeScript 7 while its JavaScript API is unavailable.

Install TypeScript 7 in your project:

pnpm add -D typescript@^7

npm install -D typescript@^7

yarn add -D typescript@^7

bun add -D typescript@^7

The CLI checker is enabled by default. To use the TypeScript JavaScript compiler API instead, set experimental.useTypeScriptCli to false:

import type { NextConfig } from 'next'
 
const nextConfig: NextConfig = {
  experimental: {
    useTypeScriptCli: false,
  },
}
 
export default nextConfig

If you opt out while using TypeScript 7, next build exits because the TypeScript JavaScript compiler API is unavailable.

Behavior

• Next.js continues to generate next-env.d.ts and route types and to apply its recommended tsconfig settings before running the checker.
• TypeScript diagnostics are printed directly from tsc. Next.js-specific code frames and error rewriting are not applied.
• The complete project selected by the configured tsconfig file is checked, including test files and .next/dev/types when included. The --debug-build-paths option does not limit this set and produces a warning when combined with the CLI checker.
• typescript.tsconfigPath selects the project passed to tsc.
• typescript.ignoreBuildErrors skips the type-checking step, including the CLI checker.

Learn more about using TypeScript 7 with Next.js.