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.