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FormSubmit

Sending submissions

Redirects & thank-you page

Control where visitors go after submitting an HTML form, or customise the hosted thank-you page.

After a successful HTML (non-JavaScript) submission, FormSubmit responds with 303 See Other. Browsers then load the next page with GET, so refreshing never re-submits the form.

Where visitors are sent

  1. Form settings → Redirect URL. Always wins when set.
  2. _redirect field (alias _next). Lets different pages use different thank-you pages:
html
<input type="hidden" name="_redirect" value="https://example.com/thanks?source=pricing">

When a domain allowlist is configured, _redirect must point to an allowed domain — this prevents your endpoint being used as an open redirect.

  1. Hosted thank-you page. A clean confirmation page at formsubmit.app/thanks showing your form's custom success title and message.

Errors

If a submission fails (for example a captcha error) HTML visitors are redirected to a friendly error page explaining what happened, with a link back. JavaScript clients receive JSON — see AJAX & JavaScript.

JavaScript submissions

Requests that ask for JSON never redirect. Use the message in the response or your own UI.