API routes

Drop a file in src/api/ and export HTTP-method handlers — they are served under /api/*.

// src/api/hello.ts  →  /api/hello
export function GET() {
  return Response.json({ message: 'hello' });
}

export function POST(request: Request) {
  return Response.json({ method: 'POST' });
}

Export one function per method you support: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS. The directory is configurable through apiDir in fluixi.config; src/api is the default.

Return values

A handler returns a Web Response, or any value — which is sent as JSON:

export function GET() {
  return { ok: true };          // → application/json
}

export function GET() {
  return Response.json({ ok: true }, { status: 201 });   // full control
}

export function GET() {
  return new Response('plain', { headers: { 'content-type': 'text/plain' } });
}

Return a Response yourself when you need a status other than 200, custom headers, a redirect, or a non-JSON body. The plain-value form exists so the common case stays short.

Params and catch-all

The file path is the route, with the same conventions as pages:

// src/api/users/[id].ts  →  /api/users/:id
export function GET(_req: Request, { params }: { params: { id: string } }) {
  return Response.json({ id: params.id });
}

// src/api/files/[...path].ts  →  catch-all, /api/files/**

Params arrive as plain strings on the second argument, not as accessors — an API handler runs once per request, so there is nothing reactive about it.

Everything else about the request comes from the standard Request: the query string via new URL(request.url).searchParams, the body via await request.json() or await request.formData(), and headers via request.headers.

Status codes you get for free

A request to a path that exists but with a method you did not export returns 405, with an Allow header listing the methods that file does export; an unknown /api/* path returns 404. You do not need to write either.

API route or server function?

Both run only on the server, so the choice is about who calls them:

• A server function is for your own client code. It is typed end to end, and the call looks like a function call rather than a fetch.
• An API route is for callers you do not control — a webhook, a mobile app, a CLI, anything that needs a stable URL, a specific status code, or a non-JSON body.

If you are reaching for fetch('/api/…') inside your own app, a server function is usually the shorter path.

Next: Middleware.