Signup Form in HTML — Working Code with Validation

<form action="https://splitforms.com/api/submit" method="POST">
  <input type="hidden" name="access_key" value="YOUR_ACCESS_KEY" />
  <input type="hidden" name="_subject"   value="New signup" />

  <label>Email<input name="email" type="email" required autocomplete="email" /></label>
  <label>Password<input name="password" type="password" required minlength="8"
                       autocomplete="new-password" /></label>
  <label>Confirm password<input name="password_confirm" type="password" required minlength="8"
                                autocomplete="new-password" /></label>

  <label>
    <input type="checkbox" name="agree_terms" required />
    I agree to the <a href="/terms">terms</a> and <a href="/privacy">privacy policy</a>
  </label>

  <input type="checkbox" name="botcheck" style="display:none" tabindex="-1" />
  <button type="submit">Sign up</button>
</form>

<script>
  const f = document.querySelector("form");
  const p = f.querySelector("[name=password]");
  const c = f.querySelector("[name=password_confirm]");
  c.addEventListener("input", () => {
    c.setCustomValidity(c.value === p.value ? "" : "Passwords don't match");
  });
</script>

A signup form is a registration form's shorter sibling — typically just email + password + terms, without the full name field. Same mechanics, fewer fields. For lead-gen signups (newsletter, waitlist, beta access), even simpler — just email + agree.

The form above uses all the right autofill attributes. `autocomplete="email"` triggers email autofill on every browser. `autocomplete="new-password"` tells password managers to generate and save a new password (not autofill an existing one). Skip these and password managers misbehave.

The terms checkbox uses `required` so the browser blocks submission until checked. Browsers display 'You must accept the terms' inline — no custom JavaScript validation needed. This is the kind of small detail that converts: don't write a JS handler for what HTML already does.

The form POSTs to splitforms. For real account creation, configure a webhook in the splitforms dashboard pointing at your auth provider's signup endpoint (Supabase, Clerk, Auth0, your own /api/register). The webhook fires on every signup; your auth provider creates the user.

Email + password + terms checkbox. Five JS lines for password match. Done.