diff --git a/templates/devtest/gitea-ui.tmpl b/templates/devtest/gitea-ui.tmpl
index ea293fd3b41..06d0e36569a 100644
--- a/templates/devtest/gitea-ui.tmpl
+++ b/templates/devtest/gitea-ui.tmpl
@@ -182,15 +182,6 @@
 		</div>
 	</div>
 
-	<div>
-		<h1>Toast</h1>
-		<div>
-			<button class="ui button" id="info-toast">Show Info Toast</button>
-			<button class="ui button" id="warning-toast">Show Warning Toast</button>
-			<button class="ui button" id="error-toast">Show Error Toast</button>
-		</div>
-	</div>
-
 	<div>
 		<h1>ComboMarkdownEditor</h1>
 		<div>ps: no JS code attached, so just a layout</div>
@@ -201,7 +192,5 @@
 	<div>
 		<button class="{{if true}}tw-bg-red{{end}} tw-p-5 tw-border tw-rounded hover:tw-bg-blue active:tw-bg-yellow">Button</button>
 	</div>
-
-	<script src="{{AssetUrlPrefix}}/js/devtest.js?v={{AssetVersion}}"></script>
 </div>
 {{template "base/footer" .}}
diff --git a/templates/devtest/toast.tmpl b/templates/devtest/toast.tmpl
new file mode 100644
index 00000000000..412f23964a2
--- /dev/null
+++ b/templates/devtest/toast.tmpl
@@ -0,0 +1,15 @@
+{{template "base/head" .}}
+
+<div>
+	<h1>Toast</h1>
+	<div>
+		<button class="ui button toast-test-button" data-toast-level="info" data-toast-message="test info">Show Info Toast</button>
+		<button class="ui button toast-test-button" data-toast-level="warning" data-toast-message="test warning">Show Warning Toast</button>
+		<button class="ui button toast-test-button" data-toast-level="error" data-toast-message="test error">Show Error Toast</button>
+		<button class="ui button toast-test-button" data-toast-level="error" data-toast-message="very looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong message">Show Error Toast (long)</button>
+	</div>
+</div>
+
+<script src="{{AssetUrlPrefix}}/js/devtest.js?v={{AssetVersion}}"></script>
+
+{{template "base/footer" .}}
diff --git a/web_src/css/modules/animations.css b/web_src/css/modules/animations.css
index a86c9234aa3..481e997d4fc 100644
--- a/web_src/css/modules/animations.css
+++ b/web_src/css/modules/animations.css
@@ -92,20 +92,22 @@ code.language-math.is-loading::after {
   }
 }
 
-@keyframes pulse {
+/* 1p5 means 1-point-5. it can't use "pulse" here, otherwise the animation is not right (maybe due to some conflicts */
+@keyframes pulse-1p5 {
   0% {
     transform: scale(1);
   }
   50% {
-    transform: scale(1.8);
+    transform: scale(1.5);
   }
   100% {
     transform: scale(1);
   }
 }
 
-.pulse {
-  animation: pulse 2s linear;
+/* pulse animation for scale(1.5) in 200ms */
+.pulse-1p5-200 {
+  animation: pulse-1p5 200ms linear;
 }
 
 .ui.modal,
diff --git a/web_src/css/modules/toast.css b/web_src/css/modules/toast.css
index 2a9f78e0175..1145f3b1b58 100644
--- a/web_src/css/modules/toast.css
+++ b/web_src/css/modules/toast.css
@@ -22,17 +22,31 @@
   overflow-wrap: anywhere;
 }
 
-.toast-close,
-.toast-icon {
-  color: currentcolor;
+.toast-close {
   border-radius: var(--border-radius);
-  background: transparent;
-  border: none;
-  display: flex;
   width: 30px;
   height: 30px;
   justify-content: center;
+}
+
+.toast-icon {
+  display: inline-flex;
+  width: 30px;
+  height: 30px;
   align-items: center;
+  justify-content: center;
+}
+
+.toast-duplicate-number::before {
+  content: "(";
+}
+.toast-duplicate-number {
+  display: inline-block;
+  margin-right: 5px;
+  user-select: none;
+}
+.toast-duplicate-number::after {
+  content: ")";
 }
 
 .toast-close:hover {
diff --git a/web_src/js/features/repo-diff.js b/web_src/js/features/repo-diff.js
index cd01232a7e5..279f6da7572 100644
--- a/web_src/js/features/repo-diff.js
+++ b/web_src/js/features/repo-diff.js
@@ -7,7 +7,7 @@ import {validateTextareaNonEmpty} from './comp/ComboMarkdownEditor.js';
 import {initViewedCheckboxListenerFor, countAndUpdateViewedFiles, initExpandAndCollapseFilesButton} from './pull-view-file.js';
 import {initImageDiff} from './imagediff.js';
 import {showErrorToast} from '../modules/toast.js';
-import {submitEventSubmitter, queryElemSiblings, hideElem, showElem} from '../utils/dom.js';
+import {submitEventSubmitter, queryElemSiblings, hideElem, showElem, animateOnce} from '../utils/dom.js';
 import {POST, GET} from '../modules/fetch.js';
 
 const {pageData, i18n} = window.config;
@@ -26,11 +26,7 @@ function initRepoDiffReviewButton() {
       const num = parseInt(counter.getAttribute('data-pending-comment-number')) + 1 || 1;
       counter.setAttribute('data-pending-comment-number', num);
       counter.textContent = num;
-
-      reviewBox.classList.remove('pulse');
-      requestAnimationFrame(() => {
-        reviewBox.classList.add('pulse');
-      });
+      animateOnce(reviewBox, 'pulse-1p5-200');
     });
   });
 }
diff --git a/web_src/js/modules/toast.js b/web_src/js/modules/toast.js
index d12d203718b..627e24a1ff9 100644
--- a/web_src/js/modules/toast.js
+++ b/web_src/js/modules/toast.js
@@ -1,5 +1,6 @@
 import {htmlEscape} from 'escape-goat';
 import {svg} from '../svg.js';
+import {animateOnce, showElem} from '../utils/dom.js';
 import Toastify from 'toastify-js'; // don't use "async import", because when network error occurs, the "async import" also fails and nothing is shown
 
 const levels = {
@@ -21,13 +22,28 @@ const levels = {
 };
 
 // See https://github.com/apvarun/toastify-js#api for options
-function showToast(message, level, {gravity, position, duration, useHtmlBody, ...other} = {}) {
+function showToast(message, level, {gravity, position, duration, useHtmlBody, preventDuplicates = true, ...other} = {}) {
+  const body = useHtmlBody ? String(message) : htmlEscape(message);
+  const key = `${level}-${body}`;
+
+  // prevent showing duplicate toasts with same level and message, and give a visual feedback for end users
+  if (preventDuplicates) {
+    const toastEl = document.querySelector(`.toastify[data-toast-unique-key="${CSS.escape(key)}"]`);
+    if (toastEl) {
+      const toastDupNumEl = toastEl.querySelector('.toast-duplicate-number');
+      showElem(toastDupNumEl);
+      toastDupNumEl.textContent = String(Number(toastDupNumEl.textContent) + 1);
+      animateOnce(toastDupNumEl, 'pulse-1p5-200');
+      return;
+    }
+  }
+
   const {icon, background, duration: levelDuration} = levels[level ?? 'info'];
   const toast = Toastify({
     text: `
       <div class='toast-icon'>${svg(icon)}</div>
-      <div class='toast-body'>${useHtmlBody ? message : htmlEscape(message)}</div>
-      <button class='toast-close'>${svg('octicon-x')}</button>
+      <div class='toast-body'><span class="toast-duplicate-number tw-hidden">1</span>${body}</div>
+      <button class='btn toast-close'>${svg('octicon-x')}</button>
     `,
     escapeMarkup: false,
     gravity: gravity ?? 'top',
@@ -39,6 +55,7 @@ function showToast(message, level, {gravity, position, duration, useHtmlBody, ..
 
   toast.showToast();
   toast.toastElement.querySelector('.toast-close').addEventListener('click', () => toast.hideToast());
+  toast.toastElement.setAttribute('data-toast-unique-key', key);
   return toast;
 }
 
diff --git a/web_src/js/standalone/devtest.js b/web_src/js/standalone/devtest.js
index 8dbba554acb..d3e3e13a879 100644
--- a/web_src/js/standalone/devtest.js
+++ b/web_src/js/standalone/devtest.js
@@ -1,11 +1,14 @@
 import {showInfoToast, showWarningToast, showErrorToast} from '../modules/toast.js';
 
-document.querySelector('#info-toast').addEventListener('click', () => {
-  showInfoToast('success 😀');
-});
-document.querySelector('#warning-toast').addEventListener('click', () => {
-  showWarningToast('warning 😐');
-});
-document.querySelector('#error-toast').addEventListener('click', () => {
-  showErrorToast('error 🙁');
-});
+function initDevtestToast() {
+  const levelMap = {info: showInfoToast, warning: showWarningToast, error: showErrorToast};
+  for (const el of document.querySelectorAll('.toast-test-button')) {
+    el.addEventListener('click', () => {
+      const level = el.getAttribute('data-toast-level');
+      const message = el.getAttribute('data-toast-message');
+      levelMap[level](message);
+    });
+  }
+}
+
+initDevtestToast();
diff --git a/web_src/js/utils/dom.js b/web_src/js/utils/dom.js
index 6a38968899f..9bdb2332362 100644
--- a/web_src/js/utils/dom.js
+++ b/web_src/js/utils/dom.js
@@ -306,3 +306,14 @@ export function createElementFromAttrs(tagName, attrs) {
   }
   return el;
 }
+
+export function animateOnce(el, animationClassName) {
+  return new Promise((resolve) => {
+    el.addEventListener('animationend', function onAnimationEnd() {
+      el.classList.remove(animationClassName);
+      el.removeEventListener('animationend', onAnimationEnd);
+      resolve();
+    }, {once: true});
+    el.classList.add(animationClassName);
+  });
+}