HTTP Endpoints

HTTP Endpoints

HTTP vals (fileType: "http") export a request handler and run on every incoming HTTP request. Each HTTP file is assigned a live URL — never construct it yourself; read links.endpoint from list_files or create_file responses, or call fetch_val_endpoint.

That URL is open to anyone unless the val's app access (httpPrivacy) is restricted, in which case unauthenticated callers get a 302 to a login page instead of your response — see the restricted-access skill.

Basic handler

// Learn more: https://docs.val.town/vals/http/
export default async function (req: Request): Promise<Response> {
  return Response.json({ ok: true });
}

The file must have an export — export default for the handler.

Hono

When using Hono, export app.fetch (not app):

import { Hono } from "npm:hono";
import { parseVal, serveImmutableFile } from "https://esm.town/v/std/utils/index.ts";

const app = new Hono();

app.get("/", (c) => c.text("hello"));

// Immutable asset caching (see the client-side-js skill): serves the
// current-version URLs your HTML shell stamps with immutableFileUrl()
app.get("/__immutable/*", (c) => serveImmutableFile(c.req.path));

// View source redirect
app.get("/source", (c) => c.redirect(parseVal().links.self.val));

// Always add this for full stack traces on errors:
app.onError((err) => Promise.reject(err));

export default app.fetch;

Hono's serveStatic does not work on Val Town. Use serveFile / staticHTTPServer from std/utils for static files. For the full std/utils API (readFile, serveFile, staticHTTPServer, listFiles, listFilesByPath, httpEndpoint, parseVal, …), fetch https://utilities.val.run/docs.md.

CORS

Val Town adds permissive CORS headers by default (Access-Control-Allow-Origin: *), so in 99% of cases, you should never need to do anything with CORS. Using Hono's cors middleware is almost always unnecessary.

If you set any CORS header yourself, Val Town stops adding all default headers — so either handle CORS completely yourself or don't touch it at all.

Redirects

Response.redirect is broken on Val Town. Use one of:

return new Response(null, { status: 302, headers: { Location: "/path" } });
// or, with Hono:
return c.redirect("/path");

What's not available

• WebSockets: Val Town does not accept incoming WebSocket connections. Use polling, long polling, or server-sent events instead.
• Filesystem access: see the platform constraints. For persistent state, use std/sqlite or std/blob.

Surfacing client-side errors

For HTML responses, add this script tag to send browser errors back to val logs (visible via get_logs):

<script src="https://esm.town/v/std/catch"></script>

Verifying changes

After editing an HTTP val, fetch it to confirm it returns the expected HTTP response. Do not report a change as done without this step.