diff --git a/library/Tiger/View/Helper/FormRecaptcha.php b/library/Tiger/View/Helper/FormRecaptcha.php
index 840f2bb..6fc1ea2 100644
--- a/library/Tiger/View/Helper/FormRecaptcha.php
+++ b/library/Tiger/View/Helper/FormRecaptcha.php
@@ -72,7 +72,12 @@ protected function _v3($site, $siteEsc, array $attribs)
                 . 'document.querySelectorAll("input.g-recaptcha-response").forEach(function(inp){'
                 . 'var form=inp.form; if(!form||form.__grcBound)return; form.__grcBound=true;'
                 . 'form.addEventListener("submit",function(e){'
-                . 'if(form.__grcOk)return; e.preventDefault();'
+                // Token ready (this is the re-submit): re-arm for the NEXT submit so retries mint a fresh,
+                // unused token — a v3 token is single-use — then let the form's own handler proceed.
+                . 'if(form.__grcOk){form.__grcOk=false;return;}'
+                // First submit: HOLD the form's own submit handler (Tiger forms AJAX on submit and would
+                // otherwise fire with an empty token) until the async token exists, then re-dispatch.
+                . 'e.preventDefault(); e.stopImmediatePropagation();'
                 . 'grecaptcha.execute(' . json_encode($site) . ',{action:' . json_encode($action) . '}).then(function(t){'
                 . 'inp.value=t; form.__grcOk=true;'
                 . 'if(typeof form.requestSubmit==="function")form.requestSubmit();else form.submit();});'
diff --git a/modules/signup/languages/en/signup.php b/modules/signup/languages/en/signup.php
index a66558b..fe05709 100644
--- a/modules/signup/languages/en/signup.php
+++ b/modules/signup/languages/en/signup.php
@@ -7,6 +7,7 @@
  */
 return [
     'signup.disabled'    => 'Public signup is currently turned off.',
+    'signup.error.recaptcha' => "Couldn't verify you're human — please try again.",
     'signup.check_email' => 'Account created — check your email to verify it, then sign in.',
     'signup.verified'    => 'Your email is verified and your account is active.',
     'signup.invalid_link' => 'This verification link is invalid or has expired.',
diff --git a/modules/signup/services/Signup.php b/modules/signup/services/Signup.php
index c35cf99..623307d 100644
--- a/modules/signup/services/Signup.php
+++ b/modules/signup/services/Signup.php
@@ -41,6 +41,12 @@ public function create(array $params): void
         if (self::isPublicDisabled()) { $this->_error('signup.disabled'); return; }
         $form = new Signup_Form_Signup();
         if (!$form->isValid($params)) { $this->_formErrors($form); return; }
+        // Bot gate on this PUBLIC, account-creating endpoint — the same core reCAPTCHA validator the auth
+        // flow uses (Tiger_Validate_Recaptcha). A no-op when reCAPTCHA is disabled (the validator passes),
+        // so nothing changes on installs without keys; fail_open covers a Google outage.
+        if (!(new Tiger_Validate_Recaptcha(['action' => 'signup']))->isValid(null, $params)) {
+            $this->_error('signup.error.recaptcha'); return;
+        }
         $v = $form->getValues();
 
         try {
diff --git a/modules/signup/views/scripts/index/index.phtml b/modules/signup/views/scripts/index/index.phtml
index ed30b76..96c6651 100644
--- a/modules/signup/views/scripts/index/index.phtml
+++ b/modules/signup/views/scripts/index/index.phtml
@@ -9,6 +9,9 @@
  */
 $form = $this->form;
 $el = function ($name) use ($form) { return $form->getElement($name); };
+// v3 site key for the JS to mint a token before this button-click AJAX submit (empty when off / v2).
+$rcSite = (class_exists('Tiger_Recaptcha') && Tiger_Recaptcha::isEnabled() && Tiger_Recaptcha::version() === 'v3')
+    ? (string) Tiger_Recaptcha::siteKey() : '';
 ?>
 <div class="tiger-auth-brand">
     <span class="tiger-auth-mark"><i class="fa-solid fa-paw"></i></span>
@@ -19,8 +22,10 @@ $el = function ($name) use ($form) { return $form->getElement($name); };
 <div id="signup-feedback"></div>
 <div id="signup-done"></div>
 
-<form id="signup-form" data-tiger-validate data-module="signup" data-form="Signup" onsubmit="return false;" novalidate>
+<form id="signup-form" data-tiger-validate data-module="signup" data-form="Signup" onsubmit="return false;" novalidate data-recaptcha-site="<?= $this->escape($rcSite) ?>">
     <?= $el('_csrf') ?>
+    <?php /* Core reCAPTCHA (loads api.js + the badge/legal notice + a hidden g-recaptcha-response); the token is minted in JS before this AJAX submit. */ ?>
+    <?= $this->formRecaptcha('g-recaptcha-response', null, ['action' => 'signup']) ?>
 
     <div class="row g-3">
         <div class="col-sm-6" data-field>
@@ -116,11 +121,21 @@ $el = function ($name) use ($form) { return $form->getElement($name); };
 document.addEventListener('DOMContentLoaded', function () {
     var form = document.getElementById('signup-form');
     var fb   = document.getElementById('signup-feedback');
+    var rcSite = form.getAttribute('data-recaptcha-site') || '';   // v3 site key (empty = off/v2 → skip)
+    function rcToken(action) {
+        if (!rcSite || !window.grecaptcha) { return Promise.resolve(''); }
+        return new Promise(function (resolve) {
+            try { grecaptcha.ready(function () { grecaptcha.execute(rcSite, { action: action }).then(resolve, function () { resolve(''); }); }); }
+            catch (e) { resolve(''); }
+        });
+    }
 
     document.getElementById('signup-submit').addEventListener('click', function () {
         var btn = this;
         form.querySelectorAll('.is-invalid').forEach(function (e) { e.classList.remove('is-invalid'); });
-
+        rcToken('signup').then(function (token) {
+        var hid = form.querySelector('input.g-recaptcha-response');
+        if (hid && token) { hid.value = token; }
         var fd = new URLSearchParams(new FormData(form));
         fd.set('module', 'signup'); fd.set('service', 'signup'); fd.set('method', 'create');
 
@@ -156,6 +171,7 @@ document.addEventListener('DOMContentLoaded', function () {
         }).catch(function () {
             TigerDOM.notify(fb, 'Network error — please try again.', { type: 'error' });
         });
+        });
     });
 });
 </script>