Next.js Route Segment Config
Behind the friendly file conventions of the App Router — page.js, layout.js, route.js — sits a small set of plain exported variables that let you override specific rendering behaviors for that one segment: which runtime it executes in, how long it's allowed to run, whether unlisted dynamic params should even be attempted. Collectively, these are the Route Segment Config options, and this article is the map to the individual, dedicated references covering each one in depth.
How It Works
Every option in this family is just a named export from page.js, layout.js, or route.js — no special syntax, no wrapper function, just a constant:
export const runtime = "nodejs";
export const maxDuration = 30;
Next.js recognizes these specific export names at build time and adjusts the segment's behavior accordingly. You opt in only to the ones you actually need to override; every option has a sensible default that applies if you don't export it at all.
The Current Option Set
| Option | Type | Default |
|---|---|---|
dynamicParams | boolean | true |
runtime | 'nodejs' | 'edge' (edge deprecated) | 'nodejs' |
preferredRegion | 'auto' | 'global' | 'home' | string | string[] (deprecated) | 'auto' |
maxDuration | number | Set by your deployment platform |
Alongside these four, two more options round out the current set: instant (controlling instant-navigation behavior) and prefetch (controlling prefetch behavior for a segment) — both are covered in their own dedicated references, since each has enough nuance to warrant a full article rather than a single table row.
A Meaningful Recent Change: Options That No Longer Exist Here
If you're coming from an older Next.js codebase, or reading older tutorials, you'll likely encounter route segment config options that aren't in this current list at all: dynamic, revalidate, and fetchCache. This isn't an oversight in this reference — as of a recent major version, these three options are removed entirely once Cache Components is enabled, because the caching model they controlled has been replaced by the newer use cache directive-based system.
If your project has Cache Components enabled and you're still exporting export const revalidate = 60 expecting it to do something, it won't — that entire configuration surface belongs to the previous caching model, documented separately as "Caching and Revalidating (Previous Model)" for projects that haven't adopted Cache Components yet. Migrating a route that still uses these older exports means moving to the use cache directive and cacheLife/cacheTag instead, not simply carrying the old exports forward unchanged.
A second, related removal worth flagging if you're maintaining an older codebase: export const experimental_ppr = true was also removed as of the same version. A dedicated codemod exists specifically to strip this now-meaningless export from your Pages and Layouts automatically, rather than requiring a manual find-and-remove across your whole codebase.
A Deprecation Worth Tracking If You're on Edge Runtime
export const runtime = "experimental-edge" — the older string value for opting a segment into the Edge runtime — was deprecated as of Next.js 15. A codemod exists to transform this value to the current, non-experimental "edge" string automatically. If your codebase predates this change and still has experimental-edge scattered across route files, running that codemod is the recommended path rather than hand-editing every occurrence.
The Individual References
Each option below has genuinely distinct enough behavior, edge cases, and defaults to warrant its own dedicated article rather than a shared page:
| Option | What it controls |
|---|---|
dynamicParams | Whether requests for dynamic segments not returned by generateStaticParams are still handled, or 404 immediately |
instant | Instant-navigation behavior for a segment |
maxDuration | The maximum execution time allowed for a segment's server-side work |
preferredRegion (deprecated) | Which deployment region a segment prefers to execute in |
prefetch | Prefetch behavior for a segment's links |
runtime | Whether a segment executes in the Node.js or Edge runtime |
Version History
| Version | Change |
|---|---|
v16.0.0 | dynamic, dynamicParams, revalidate, and fetchCache removed when Cache Components is enabled — see the Previous Model caching guide for the older, still-supported alternative |
v16.0.0 | export const experimental_ppr = true removed; a codemod is available |
v15.0.0-RC | export const runtime = "experimental-edge" deprecated; a codemod is available |
Key Takeaways
| Concept | Detail |
|---|---|
| Mechanism | Plain named exports from page.js, layout.js, or route.js — no special syntax |
| Current core options | dynamicParams, runtime, preferredRegion, maxDuration, plus instant and prefetch |
| Removed under Cache Components | dynamic, revalidate, fetchCache — replaced by use cache, cacheLife, and cacheTag |
experimental_ppr | Removed entirely; a codemod cleans it up automatically |
runtime value migration | "experimental-edge" → "edge", via codemod |
The single most important thing to take from this overview, if you're working in a codebase that predates Cache Components, is that route segment config isn't a static, fixed API — three of its most commonly used options were deliberately retired as the caching model evolved. Before reaching for revalidate or fetchCache in new code, confirm which caching model your project is actually on; using the wrong generation's options silently does nothing rather than raising a helpful error.
