Plain HTML

No framework, no build, no JS. Drop a form on any page and you're done.

The four lines

<form action="https://formspring.io/f/r2EdO-orF-3S" method="POST">
  <input name="email" type="email" required />
  <textarea name="message" required></textarea>
  <button>Send</button>
</form>

That's it. The browser handles validation. Formspring accepts the POST, returns a 200 HTML page, you're done.

With a thank-you redirect

Add a hidden field. Formspring 303s the user to that URL after a successful submission:

<form action="https://formspring.io/f/r2EdO-orF-3S" method="POST">
  <input type="hidden" name="_redirect" value="https://example.com/thanks" />
  <input name="email" type="email" required />
  <textarea name="message" required></textarea>
  <button>Send</button>
</form>

The redirect target must be an absolute URL on a domain you've added to the form's allowlist (set in Form settings → Domains).

Honeypot

Add a hidden field bots will fill but humans won't. We drop submissions where it's not empty.

<form action="https://formspring.io/f/r2EdO-orF-3S" method="POST">
  <input type="text" name="_gotcha" tabindex="-1" autocomplete="off"
         style="position:absolute;left:-9999px;" aria-hidden="true" />

  <input name="email" type="email" required />
  <textarea name="message" required></textarea>
  <button>Send</button>
</form>

Don't use display: none — some bots ignore styles entirely or scrape the rendered DOM. Move the field offscreen instead.

Native validation

The browser handles required fields, email format, pattern matching, and min/max lengths.

<input name="email" type="email" required />
<input name="phone" type="tel" pattern="[0-9 +()-]{6,}" />
<input name="age" type="number" min="18" max="120" />
<textarea name="message" required minlength="10" maxlength="1000"></textarea>

The browser surfaces errors automatically; no JS. Add novalidate to the form if you want to skip browser validation and rely entirely on Formspring's server-side validation.

Multiple checkboxes / multi-select

Use the same name for related checkboxes. Formspring receives an array.

<fieldset>
  <legend>Interested in</legend>
  <label><input type="checkbox" name="interests[]" value="forms" /> Forms</label>
  <label><input type="checkbox" name="interests[]" value="webhooks" /> Webhooks</label>
  <label><input type="checkbox" name="interests[]" value="ai" /> AI features</label>
</fieldset>

The submission's payload.interests will be a JSON array.

File upload

<form action="https://formspring.io/f/r2EdO-orF-3S" method="POST" enctype="multipart/form-data">
  <input name="email" type="email" required />
  <input name="attachment" type="file" />
  <button>Send</button>
</form>

enctype="multipart/form-data" is required for file uploads; without it the browser sends only filenames, not bytes. Files are stored, scanned, and exposed as signed URLs in webhooks.

What plain HTML can't do

Inline error rendering (the user gets redirected on failure too unless you add JS).
Optimistic UI / loading state.
Any kind of multi-step flow.

For any of those, pick a framework recipe — Next.js, SvelteKit, Astro, or just vanilla React.