Top Next.js TypeScript Tips You Probably Didn’t Know in 2025

Introduction

When you create a Next.js project using the TypeScript template, it’s easy to feel like you’re already getting all the type safety that TypeScript can offer. But the truth is: you’re only halfway there.

Most developers unknowingly use just the basic TypeScript features while ignoring the powerful, framework-specific typings built directly into Next.js. These features are rarely discussed, hidden behind experimental flags, or tucked away in documentation that most developers never read.

This article will walk you through the most important Next.js TypeScript tricks of 2025 — from typed routes to typed environment variables, from custom IntelliSense to route-aware helper types. By the end of this guide, your project will be significantly more robust, maintainable, and error-free.

1. Next.js Has Its Own Custom Type Checker — And You Probably Haven’t Enabled It

When working with TypeScript inside Next.js, most developers assume the language server they use is the same as the one powering the framework. But that’s not true.

Next.js ships with its own custom TypeScript plugin that enhances IntelliSense with framework-specific features that plain TypeScript simply cannot understand.

How to Activate the Custom Type Checker

To enable Next.js’s enhanced TypeScript engine in VS Code:

1. Open your project in VS Code
2. Press Ctrl + Shift + P (or Cmd + Shift + P on Mac)
3. Type: “TypeScript: Select TypeScript Version”
4. Choose: Use Workspace Version

Once activated, VS Code creates:

.vscode/settings.json

With:

{
  "typescript.tsdk": "node_modules/typescript/lib"
}

This tells the editor: use the project's local TypeScript version, which is where Next.js injects its custom plugin.

What This Unlocks

The custom type checker adds deep language support for Next.js-specific conventions:

• IntelliSense for special Next.js exports
• IntelliSense for export const dynamic, revalidate, fetchCache, etc.
• Error detection when "use client" is placed incorrectly
• Framework-aware type rules
• Stricter and more accurate validation for server/client files

For example:

export const dynamic = "force-static";

As soon as you type "force-", VS Code suggests all valid values. Vanilla TypeScript can't do this because it has no idea what a Next.js “route segment config” is.

Why It Matters

This makes you:

• Faster (less documentation searching)
• More accurate (fewer silent mistakes)
• More confident (Next.js prevents invalid values)

This one step alone can dramatically improve the correctness of your app.

2. Typed Routes — The Most Powerful Next.js Feature Nobody Talks About

Typed routes bring Next.js closer to frameworks like Remix or Solid Start, where route awareness is built into the compiler.

With typed routes, your entire app becomes more reliable because every link becomes type-checked.

How to Enable Typed Routes

Add this to your next.config.ts:

export default {
  experimental: {
    typedRoutes: true,
  },
};

When you start the dev server or run a build, Next.js generates a dynamic file:

.next/types/routes.d.ts

This file contains a strongly typed map of every route in your project, including:

• Static routes
• Dynamic routes
• Nested routes
• Catch-all routes

Typed Routes in Action

import Link from "next/link";

export default function Page() {
  return <Link href="/login">Login</Link>;
}

If /login doesn’t exist, TypeScript will give you a compile error.

Dynamic Route Validation

If you try:

<Link href="/slot/[slotId]">Go</Link>

You’ll get a type error because you must supply params.

Correct version:

<Link href={{ pathname: "/slot/[slotId]", params: { slotId: "123" } }}>
  Go
</Link>

Benefits of Typed Routes

• Zero broken links
• Zero typos (/logni)
• Zero missing route params
• Instant autocomplete for valid URLs
• Production-level safety during development

This feature alone can remove an entire class of runtime bugs.

3. Route-Aware Type Helpers: PageProps & LayoutProps

Next.js now gives you advanced helper types that automatically infer route params for pages and layouts.

This means you no longer need to manually write:

params: { slotId: string }

Example Dynamic Route

app/slot/[slotId]/page.tsx

Old Way (long & repetitive)

export default async function Page({
  params,
  searchParams,
}: {
  params: { slotId: string };
  searchParams: Record<string, string | string[]>;
}) {
  console.log(params.slotId);
}

New Clean Way (2025+)

export default async function Page(
  props: PageProps<"/slot/[slotId]">
) {
  const params = await props.params;

  return <div>Slot: {params.slotId}</div>;
}

What This Gives You

• Typed params
• Typed searchParams
• Typed children in layouts
• Fully inferred values
• Cleaner and more readable code

Bonus: Works in Layouts Too

export default function Layout(
  props: LayoutProps<"/slot/[slotId]">
) {
  return <>{props.children}</>;
}

Why It Matters

Your components become:

• Shorter
• Cleaner
• Easier to maintain
• Less error-prone

And you remove all manual type definitions.

4. Typed Environment Variables — Finally Typed process.env

By default, Node.js exposes all env variables as:

process.env.XYZ // string | undefined

This is dangerous because:

• You can typo env variable names
• You might assume it exists when it doesn’t
• It makes refactoring risky

Next.js solves this by providing typed environment variables.

How to Enable

Inside next.config.ts:

export default {
  experimental: {
    typedEnv: true,
  },
};

Restart your dev server once.

Next.js now generates type definitions based on .env.local, .env, .env.production, etc.

Example

process.env.TEST_SECRET;

VS Code now:

• Suggests the name automatically
• Knows whether it's required
• Knows whether it’s server-only or client-exposed
• Prevents typos

This greatly reduces errors when working with credentials, API keys, and sensitive configuration.

5. Additional TypeScript Features You Should Be Using in Next.js

Beyond the major features above, Next.js includes several additional improvements for TS-heavy codebases.

Let’s explore them.

✔ Use Next.js’s Request/Response Types

Instead of using the Web standard:

export function GET(req: Request) {}

Use Next.js’s extended types:

import { NextRequest, NextResponse } from "next/server";

export function GET(req: NextRequest) {
  return NextResponse.json({ ok: true });
}

Advantages

• Access cookies with req.cookies
• Access geo, IP, user agent
• Cleaner access to URL parameters
• Better type safety
• Ability to call NextResponse.redirect(), etc.

These types give you better DX for building APIs, middleware, and route handlers.

✔ Your next.config.ts Should Also Be Typed

Instead of using a plain JavaScript file, use a typed config:

import { NextConfig } from "next";

const config: NextConfig = {
  experimental: {
    typedRoutes: true,
    typedEnv: true,
  },
};

export default config;

This gives you:

• autocomplete for every config option
• type-checking for deprecated fields
• safety when upgrading Next.js
• better maintainability

✔ Typed File Conventions

Next.js uses file conventions like:

• loading.tsx
• error.tsx
• layout.tsx
• page.tsx

Each of these has automatic type inference baked in.

For example, error.tsx receives:

{
  error: Error;
  reset: () => void;
}

This means you never need to manually annotate them.

6. Why Type Safety Matters in Modern Next.js Apps

As applications scale, runtime errors become expensive.

TypeScript in Next.js prevents:

• Invalid routes
• Missing parameters
• Typos in env variables
• Incorrect server/client boundaries
• Wrong config values
• Invalid Next.js exports
• Errors in layouts/pages

This leads to:

• fewer production bugs
• faster development
• safer refactoring
• easier onboarding for new developers

If you're building dashboards, SaaS apps, AI tools, or anything with complexity — strong type safety is critical.

Conclusion

Next.js has evolved into a deeply TypeScript-integrated framework, but most developers only use a fraction of its capabilities.

By enabling the right features and using the right helper types, your app becomes:

• safer
• more maintainable
• more scalable
• easier to work on
• significantly more reliable

Quick Start Checklist

• Enable custom TypeScript plugin: ✅
• Use typed routes: ✅
• Use PageProps & LayoutProps: ✅
• Enable typed env variables: ✅
• Use NextRequest & NextResponse: ✅
• Use next.config.ts: ✅

If you apply everything in this guide, you will instantly upgrade your TypeScript safety from "basic usage" to "framework-level deep safety".

Modern Next.js apps rely heavily on these features — and now you know how to use them correctly.

Which Next.js TypeScript feature did you find the most useful?
Let me know if you want a version of this guide focused on server components, React Server Actions, or Next.js caching strategy.