Cloudflare Workers contact form proxy �Formspree alternative with AI spam filtering

A Cloudflare Worker that receives browser submissions and forwards them to SmartForm AI. Use this instead of the Vercel Function when you want to host everything on Cloudflare.

What you're POSTing

The endpoint accepts a standard HTML form POST or JSON via AJAX. Two kinds of fields:

Your form fields â€?name, email, message, whatever you want. Every non-reserved field lands in your dashboard as a column in the submissions table.

Reserved fields â€?names starting with _ are interpreted by the API, not stored:

Field	Purpose
_gotcha	Honeypot. Keep it empty. Hidden from humans via CSS; bots fill it automatically. Any non-empty value silently drops the submission. Add this to every form.
_hp_email / _website / _url / _phone	Honeypot aliases for _gotcha (WordPress / WPForms / Contact Form 7 migrations). Same drop semantics.
_next	Same-origin URL to redirect to after a successful submission. Browser POST results in a 302 here. AJAX calls (with Accept: application/json) get the same value back as next_url in the JSON response. Only http(s) and in-site paths allowed.
_subject	Override the AI-generated email subject line. Max 200 chars; control characters stripped.
X-Gotcha header	Same as _gotcha for JSON requests where you can't add a hidden form field.

Field names are Formspree-compatible â€?migrating from formspree.io/f/{form_id} requires no renaming.

Setup

1. Get a form ID at https://usesmartform.com/dashboard.
2. Configure secrets:

   git clone https://github.com/smartformai/smartform-example-serverless-cloudflare.git
   cd smartform-example-serverless-cloudflare
   wrangler kv:namespace create SESSIONS   # optional �only if you add rate-limit caching
   npx wrangler secret put SMARTFORM_ENDPOINT     # https://api.usesmartform.com
   npx wrangler secret put SMARTFORM_FORM_ID      # your_real_id
   npx wrangler deploy

3. Browser calls POST https://your-worker.workers.dev/submit. The Worker forwards to SmartForm.

The Worker

// src/index.ts
export interface Env { SMARTFORM_ENDPOINT: string; SMARTFORM_FORM_ID: string; }

export default {
  async fetch(req: Request, env: Env): Promise<Response> {
    if (req.method !== 'POST' || new URL(req.url).pathname !== '/submit') {
      return new Response('Not Found', { status: 404 });
    }

    const body = await req.json();
    const r = await fetch(`${env.SMARTFORM_ENDPOINT}/api/v1/f/${env.SMARTFORM_FORM_ID}`, {
      method:  'POST',
      headers: { 'Content-Type': 'application/json', 'Accept': 'application/json' },
      body:    JSON.stringify(body),
    });

    return new Response(await r.text(), {
      status:  r.status,
      headers: {
        'Content-Type':  'application/json',
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'POST, OPTIONS',
        'Access-Control-Allow-Headers': 'Content-Type',
      },
    });
  },
};

wrangler.toml declares the Worker name and compatibility date; deploy with wrangler deploy.

Static demo page

index.html is a plain HTML page that posts JSON to /submit on the Worker origin and renders the response inline.

How the SmartForm API works

• POST {endpoint}/api/v1/f/{form_id} â€?JSON or form-data, no API key.
• Response: { success, message, submission_id, is_spam, intent, next_url }.

For the full contract, see https://usesmartform.com/docs.

FAQ

Is there a free tier?

Yes. AI spam filtering is enabled by default on every plan. AI intent classification and high-value lead detection require a paid plan (Pro or Business) �the dashboard enforces this and returns HTTP 402 if you try to enable them on a free workspace.

Do I need an API key?

No. The form posts directly to a public endpoint using only an 8-char form ID, which is non-enumerable. The example also includes a hidden _gotcha honeypot field so naive bots cannot submit.

Why use a Worker?

The Worker hides the form ID and lets you add KV-based rate limiting in front of the public endpoint. Pure edge �no cold starts.

Related examples

Vercel Functions proxy | Cloudflare Pages contact form | Astro contact form

License

MIT.