Netlify contact form (Netlify Forms alternative) with AI spam filtering

Two ways to add a SmartForm contact form to a Netlify-hosted site.

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. Clone, configure, deploy:

   git clone https://github.com/smartformai/smartform-example-netlify.git
   cd smartform-example-netlify
   # edit netlify.toml �context "production" env SMARTFORM_FORM_ID
   npx netlify deploy --prod

3. Open the deployed URL, submit, check your dashboard.

Option A �pure static HTML form (no Netlify Functions)

index.html ships a plain HTML form that posts directly to SmartForm's public endpoint. Netlify's static hosting serves it; there is no Netlify Function involved.

<form action="https://api.usesmartform.com/api/v1/f/YOUR_FORM_ID" method="POST">
  <input  name="name"    required />
  <input  name="email"   type="email" required />
  <textarea name="message" required></textarea>
  <input  type="text" name="_gotcha" tabindex="-1" autocomplete="off"
          style="position:absolute;left:-9999px" aria-hidden="true" />
  <button type="submit">Send</button>
</form>

Replace YOUR_FORM_ID with the 8-char ID from your dashboard.

Option B �Netlify Function proxy

netlify/functions/submit.mjs is a small serverless function that forwards browser submissions to SmartForm. Use this when you want to:

• Keep the form ID out of the public HTML.
• Add validation or field normalization before forwarding.
• Reuse an existing Netlify Function codebase.

The browser calls /.netlify/functions/submit and the function does the upstream POST.

How the API works

• POST https://api.usesmartform.com/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.

How is this different from Netlify Forms?

Netlify Forms is bound to Netlify hosting. This example works on any static host and adds an AI spam filter instead of honeypot-only detection.

Related examples

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

License

MIT.