diff --git a/src/lib/client/ui/form/MarkdownInput.svelte b/src/lib/client/ui/form/MarkdownInput.svelte
new file mode 100644
index 0000000..194caaf
--- /dev/null
+++ b/src/lib/client/ui/form/MarkdownInput.svelte
@@ -0,0 +1,294 @@
+<script lang="ts">
+	import { Bold, Italic, List, ListOrdered, Link, Code, Eye, Edit3 } from 'lucide-svelte';
+	import { onMount } from 'svelte';
+
+	// Props
+	export let value: string = '';
+	export let placeholder: string = '';
+	export let label: string = '';
+	export let description: string = '';
+	export let rows: number = 4;
+	export let minRows: number = 2;
+	export let multiline: boolean = true;
+	export let markdown: boolean = true;
+	export let required: boolean = false;
+	export let disabled: boolean = false;
+	export let name: string = '';
+	export let id: string = name;
+	export let autoResize: boolean = true;
+	export let onchange: ((value: string) => void) | undefined = undefined;
+
+	// State
+	let showPreview = true;
+	let textareaElement: HTMLTextAreaElement;
+	let inputElement: HTMLInputElement;
+
+	// Auto-resize textarea to fit content
+	function resizeTextarea() {
+		if (!textareaElement || !autoResize || !multiline) return;
+
+		// Reset height to auto to get the correct scrollHeight
+		textareaElement.style.height = 'auto';
+
+		// Calculate min height based on minRows
+		const lineHeight = parseFloat(getComputedStyle(textareaElement).lineHeight) || 20;
+		const paddingTop = parseFloat(getComputedStyle(textareaElement).paddingTop) || 8;
+		const paddingBottom = parseFloat(getComputedStyle(textareaElement).paddingBottom) || 8;
+		const minHeight = lineHeight * minRows + paddingTop + paddingBottom;
+
+		// Set height to scrollHeight (actual content height) or minHeight
+		const newHeight = Math.max(textareaElement.scrollHeight, minHeight);
+		textareaElement.style.height = `${newHeight}px`;
+	}
+
+	function handleInput(e: Event) {
+		const target = e.target as HTMLInputElement | HTMLTextAreaElement;
+		value = target.value;
+		onchange?.(value);
+		resizeTextarea();
+	}
+
+	// Resize on mount and when value changes externally
+	onMount(() => {
+		resizeTextarea();
+	});
+
+	$: if (textareaElement && value !== undefined) {
+		// Use requestAnimationFrame to ensure DOM is updated
+		requestAnimationFrame(resizeTextarea);
+	}
+
+	function insertMarkdown(before: string, after: string = '') {
+		const element = multiline ? textareaElement : inputElement;
+		if (!element) return;
+
+		const start = element.selectionStart ?? 0;
+		const end = element.selectionEnd ?? 0;
+		const selectedText = value.substring(start, end);
+
+		const newValue =
+			value.substring(0, start) + before + selectedText + after + value.substring(end);
+
+		value = newValue;
+		onchange?.(value);
+
+		// Restore cursor position and resize
+		requestAnimationFrame(() => {
+			element.focus();
+			element.setSelectionRange(
+				start + before.length,
+				start + before.length + selectedText.length
+			);
+			resizeTextarea();
+		});
+	}
+
+	function insertBold() {
+		insertMarkdown('**', '**');
+	}
+
+	function insertItalic() {
+		insertMarkdown('*', '*');
+	}
+
+	function insertCode() {
+		insertMarkdown('`', '`');
+	}
+
+	function insertLink() {
+		const element = multiline ? textareaElement : inputElement;
+		if (!element) return;
+
+		const start = element.selectionStart ?? 0;
+		const end = element.selectionEnd ?? 0;
+		const selectedText = value.substring(start, end);
+
+		if (selectedText) {
+			insertMarkdown('[', '](url)');
+		} else {
+			insertMarkdown('[link text](url)');
+		}
+	}
+
+	function insertList() {
+		const element = multiline ? textareaElement : inputElement;
+		if (!element) return;
+
+		const start = element.selectionStart ?? 0;
+		const lines = value.substring(0, start).split('\n');
+		const isStartOfLine = lines[lines.length - 1].length === 0 || start === 0;
+
+		if (isStartOfLine) {
+			insertMarkdown('- ');
+		} else {
+			insertMarkdown('\n- ');
+		}
+	}
+
+	function insertOrderedList() {
+		const element = multiline ? textareaElement : inputElement;
+		if (!element) return;
+
+		const start = element.selectionStart ?? 0;
+		const lines = value.substring(0, start).split('\n');
+		const isStartOfLine = lines[lines.length - 1].length === 0 || start === 0;
+
+		if (isStartOfLine) {
+			insertMarkdown('1. ');
+		} else {
+			insertMarkdown('\n1. ');
+		}
+	}
+
+	// Simple markdown to HTML renderer for preview
+	function renderMarkdown(text: string): string {
+		if (!text) return '<p class="text-neutral-400 dark:text-neutral-500 italic">Nothing to preview</p>';
+
+		let html = text
+			// Escape HTML
+			.replace(/&/g, '&amp;')
+			.replace(/</g, '&lt;')
+			.replace(/>/g, '&gt;')
+			// Bold
+			.replace(/\*\*(.+?)\*\*/g, '<strong>$1</strong>')
+			// Italic
+			.replace(/\*(.+?)\*/g, '<em>$1</em>')
+			// Inline code
+			.replace(/`(.+?)`/g, '<code class="px-1 py-0.5 rounded bg-neutral-100 dark:bg-neutral-800 text-sm font-mono">$1</code>')
+			// Links
+			.replace(/\[(.+?)\]\((.+?)\)/g, '<a href="$2" class="text-accent-600 dark:text-accent-400 underline" target="_blank" rel="noopener">$1</a>')
+			// Escaped newlines (literal \n)
+			.replace(/\\n/g, '\n')
+			// Line breaks
+			.replace(/\n/g, '<br>');
+
+		// Unordered lists
+		html = html.replace(/(?:^|<br>)- (.+?)(?=<br>|$)/g, '<li class="ml-4 list-disc">$1</li>');
+
+		// Ordered lists
+		html = html.replace(/(?:^|<br>)\d+\. (.+?)(?=<br>|$)/g, '<li class="ml-4 list-decimal">$1</li>');
+
+		return html;
+	}
+
+	const toolbarButtons = [
+		{ action: insertBold, icon: Bold, title: 'Bold (Ctrl+B)', shortcut: 'b' },
+		{ action: insertItalic, icon: Italic, title: 'Italic (Ctrl+I)', shortcut: 'i' },
+		{ action: insertCode, icon: Code, title: 'Code', shortcut: null },
+		{ action: insertLink, icon: Link, title: 'Link', shortcut: null },
+		{ action: insertList, icon: List, title: 'Bullet List', shortcut: null },
+		{ action: insertOrderedList, icon: ListOrdered, title: 'Numbered List', shortcut: null }
+	];
+
+	function handleKeydown(e: KeyboardEvent) {
+		if (!markdown) return;
+
+		if (e.ctrlKey || e.metaKey) {
+			switch (e.key.toLowerCase()) {
+				case 'b':
+					e.preventDefault();
+					insertBold();
+					break;
+				case 'i':
+					e.preventDefault();
+					insertItalic();
+					break;
+			}
+		}
+	}
+</script>
+
+<div class="space-y-2">
+	{#if label}
+		<label for={id} class="block text-sm font-medium text-neutral-700 dark:text-neutral-300">
+			{label}
+			{#if required}
+				<span class="text-red-500">*</span>
+			{/if}
+		</label>
+	{/if}
+
+	{#if description}
+		<p class="text-xs text-neutral-500 dark:text-neutral-400">
+			{description}
+		</p>
+	{/if}
+
+	<!-- Input container - no gap between toolbar and input -->
+	<div>
+		{#if markdown}
+			<!-- Toolbar -->
+			<div class="flex items-center justify-between rounded-t-lg border border-neutral-300 bg-neutral-50 px-2 py-1 dark:border-neutral-700 dark:bg-neutral-800/50 {showPreview ? 'border-b-0' : ''}">
+				<div class="flex items-center gap-1">
+					{#each toolbarButtons as btn}
+						<button
+							type="button"
+							onclick={btn.action}
+							title={btn.title}
+							disabled={disabled || showPreview}
+							class="rounded p-1.5 text-neutral-600 transition-colors hover:bg-neutral-200 hover:text-neutral-900 disabled:cursor-not-allowed disabled:opacity-50 dark:text-neutral-400 dark:hover:bg-neutral-700 dark:hover:text-neutral-100"
+						>
+							<svelte:component this={btn.icon} size={16} />
+						</button>
+					{/each}
+				</div>
+				<button
+					type="button"
+					onclick={() => (showPreview = !showPreview)}
+					title={showPreview ? 'Edit' : 'Preview'}
+					class="flex items-center gap-1.5 rounded px-2 py-1 text-xs font-medium transition-colors {showPreview
+						? 'bg-accent-100 text-accent-700 dark:bg-accent-900/30 dark:text-accent-400'
+						: 'text-neutral-600 hover:bg-neutral-200 dark:text-neutral-400 dark:hover:bg-neutral-700'}"
+				>
+					{#if showPreview}
+						<Edit3 size={14} />
+						Edit
+					{:else}
+						<Eye size={14} />
+						Preview
+					{/if}
+				</button>
+			</div>
+		{/if}
+
+		{#if showPreview && markdown}
+			<!-- Preview -->
+			<div
+				class="rounded-b-lg border border-neutral-300 bg-white px-3 py-2 text-sm leading-loose text-neutral-900 dark:border-neutral-700 dark:bg-neutral-800 dark:text-neutral-100"
+				style="min-height: {minRows * 1.5}rem"
+			>
+				{@html renderMarkdown(value)}
+			</div>
+		{:else if multiline}
+			<!-- Textarea -->
+			<textarea
+				bind:this={textareaElement}
+				{id}
+				{name}
+				{value}
+				{placeholder}
+				rows={autoResize ? minRows : rows}
+				{disabled}
+				{required}
+				oninput={handleInput}
+				onkeydown={handleKeydown}
+				class="{markdown ? 'rounded-b-lg rounded-t-none border-t-0' : 'rounded-lg'} {autoResize ? 'resize-none overflow-hidden' : ''} block w-full border border-neutral-300 bg-white px-3 py-2 text-sm leading-loose text-neutral-900 placeholder-neutral-400 transition-colors focus:outline-none disabled:cursor-not-allowed disabled:bg-neutral-100 disabled:text-neutral-500 dark:border-neutral-700 dark:bg-neutral-800 dark:text-neutral-100 dark:placeholder-neutral-500 dark:disabled:bg-neutral-900 dark:disabled:text-neutral-600"
+			></textarea>
+		{:else}
+			<!-- Single-line input -->
+			<input
+				bind:this={inputElement}
+				type="text"
+				{id}
+				{name}
+				{value}
+				{placeholder}
+				{disabled}
+				{required}
+				oninput={handleInput}
+				onkeydown={handleKeydown}
+				class="{markdown ? 'rounded-b-lg rounded-t-none border-t-0' : 'rounded-lg'} block w-full border border-neutral-300 bg-white px-3 py-2 text-sm text-neutral-900 placeholder-neutral-400 transition-colors focus:outline-none disabled:cursor-not-allowed disabled:bg-neutral-100 disabled:text-neutral-500 dark:border-neutral-700 dark:bg-neutral-800 dark:text-neutral-100 dark:placeholder-neutral-500 dark:disabled:bg-neutral-900 dark:disabled:text-neutral-600"
+			/>
+		{/if}
+	</div>
+</div>
diff --git a/src/routes/regular-expressions/[databaseId]/components/RegularExpressionForm.svelte b/src/routes/regular-expressions/[databaseId]/components/RegularExpressionForm.svelte
index 6671dd2..f78812f 100644
--- a/src/routes/regular-expressions/[databaseId]/components/RegularExpressionForm.svelte
+++ b/src/routes/regular-expressions/[databaseId]/components/RegularExpressionForm.svelte
@@ -2,6 +2,7 @@
 	import { enhance } from '$app/forms';
 	import { tick } from 'svelte';
 	import TagInput from '$ui/form/TagInput.svelte';
+	import MarkdownInput from '$ui/form/MarkdownInput.svelte';
 	import SaveTargetModal from '$ui/modal/SaveTargetModal.svelte';
 	import RegexPatternField from './RegexPatternField.svelte';
 	import { alertStore } from '$alerts/store';
@@ -182,21 +183,16 @@
 
 				<!-- Description -->
 				<div>
-					<label for="description" class="block text-sm font-medium text-neutral-700 dark:text-neutral-300">
-						Description
-					</label>
-					<p class="mt-1 text-xs text-neutral-500 dark:text-neutral-400">
-						Supports markdown formatting
-					</p>
-					<textarea
+					<MarkdownInput
 						id="description"
 						name="description"
+						label="Description"
+						description="Describe what this pattern matches"
 						value={$current.description}
-						oninput={(e) => update('description', e.currentTarget.value)}
-						rows="3"
+						onchange={(v) => update('description', v)}
+						rows={3}
 						placeholder="What does this pattern match?"
-						class="mt-1 block w-full rounded-lg border border-neutral-300 bg-white px-3 py-2 text-sm text-neutral-900 placeholder-neutral-400 focus:border-accent-500 focus:outline-none focus:ring-1 focus:ring-accent-500 dark:border-neutral-700 dark:bg-neutral-800 dark:text-neutral-100 dark:placeholder-neutral-500"
-					></textarea>
+					/>
 				</div>
 			</div>
 		</div>