API Routes and Server Functions

How each meta-framework lets you write backend logic alongside the frontend codebase.

Next.js

Route Handlers (route.ts files under app/) let you export functions per HTTP method (GET, POST, etc.) to build REST-style endpoints, while Server Actions ("use server" functions) allow calling server-side mutations directly from components without manually wiring an API route.

Nuxt

Nuxt’s server/ directory (backed by the Nitro engine) lets you define API routes and middleware as simple files under server/api, each exporting an defineEventHandler function that runs as its own serverless-agnostic endpoint. This server layer ships as part of the same project and deploys alongside the frontend.

SvelteKit

+server.ts files define endpoints by exporting HTTP-method functions (GET, POST, etc.), coexisting with +page.svelte files in the same route folder to provide both a page and an API at once. Form actions in +page.server.ts offer a higher-level alternative for handling form submissions without a separate endpoint.

SolidStart

SolidStart uses server functions marked with a "use server"-style directive, letting you write server-only code inline with component logic that gets compiled into an RPC call from the client. This colocation avoids a separate API-route layer for most data mutations, though explicit API route files remain available for REST-style needs.

TanStack Start

TanStack Start provides server functions created with createServerFn, which run only on the server but are invoked from client code like a normal async function, with the framework handling the network call transparently. This gives colocated backend logic similar to SolidStart while still supporting standalone API route files when a REST-style endpoint is preferred.

Remix

Remix has no separate “API route” concept by default — action functions on route modules handle mutations tied to form submissions, and routes without a UI component can act as pure API endpoints (a “resource route”). This keeps backend logic tightly scoped to the route it serves.

Astro

Astro API endpoints are files under src/pages (or src/pages/api) that export HTTP-method functions instead of a component, working identically to page routes but returning a Response object. These require server rendering (via an adapter) to run per-request rather than at build time.

Qwik City

Qwik City offers server$, which wraps any function to force it to execute only on the server while remaining callable from client code as if it were local, alongside conventional endpoint files for REST-style routes. This mirrors the resumability model by keeping server-only logic clearly demarcated at the function level.