diff --git a/public/index.php b/public/index.php
index e3ab58c..b11557f 100644
--- a/public/index.php
+++ b/public/index.php
@@ -75,18 +75,19 @@ if (str_starts_with(haystack: $route, needle: '/.well-known/lnurlp/')) {
 }
 
 // Use this controller for routes that include a model ID
-if (preg_match('/^\/(address(?:\/edit|\/delete)?|transaction|user|order|quote|product|subscription|cart)\/([\w-]+)$/', $route, $matches)) {
+if (preg_match('/^\/(address(?:\/edit|\/delete)?|transaction|user|order|quote|product|subscription|cart|admin\/categories\/edit)\/([\w-]+)$/', $route, $matches)) {
     [$full, $type, $id] = $matches;
     $controller         = [
-        'address/edit'   => fn($id)   => address::edit($defaults, $id),
-        'address/delete' => fn($id) => address::delete($defaults, $id),
-        'transaction'    => fn($id)    => transaction::view($defaults, $id),
-        'user'           => fn($id)           => users::view($id),
-        'order'          => fn($id)          => orders::view($id),
-        'quote'          => fn($id)          => quotes::view($id),
-        'product'        => fn($id)        => products::view($id),
-        'subscription'   => fn($id)   => subscriptions::view($id),
-        'cart'           => fn($id)           => cart::index($id),
+        'address/edit'          => fn($id)          => address::edit($defaults, $id),
+        'address/delete'        => fn($id)        => address::delete($defaults, $id),
+        'transaction'           => fn($id)           => transaction::view($defaults, $id),
+        'user'                  => fn($id)                  => users::view($id),
+        'order'                 => fn($id)                 => orders::view($id),
+        'quote'                 => fn($id)                 => quotes::view($id),
+        'product'               => fn($id)               => products::view($id),
+        'subscription'          => fn($id)          => subscriptions::view($id),
+        'cart'                  => fn($id)                  => cart::index($id),
+        'admin/categories/edit' => fn($id) => $defaults['is_admin'] ? admin::categories_edit($defaults, $id) : lost::index($defaults),
     ];
 
     if (isset($controller[$type])) {
@@ -112,8 +113,11 @@ if (preg_match('/^\/(address(?:\/edit|\/delete)?|transaction|user|order|quote|pr
         '/account/address/set-default-billing' => $defaults['is_user'] ? account::set_default_billing($defaults) : header('Location: /account/login'),
         '/admin' => $defaults['is_admin'] ? admin::index($defaults) : lost::index($defaults),
         '/admin/users' => $defaults['is_admin'] ? admin::users($defaults) : lost::index($defaults),
+        '/admin/products' => $defaults['is_admin'] ? admin::products($defaults) : lost::index($defaults),
         '/admin/orders' => $defaults['is_admin'] ? admin::orders($defaults) : lost::index($defaults),
         '/admin/emails' => $defaults['is_admin'] ? admin::emails($defaults) : lost::index($defaults),
+        '/admin/categories' => $defaults['is_admin'] ? admin::categories($defaults) : lost::index($defaults),
+        '/admin/categories/add' => $defaults['is_admin'] ? admin::categories_add($defaults) : lost::index($defaults),
         '/admin/transactions' => $defaults['is_admin'] ? admin::transactions($defaults) : lost::index($defaults),
         '/admin/transactions/add' => $defaults['is_admin'] ? admin::transactions_add($defaults) : lost::index($defaults),
         '/admin/transactions/reset' => $defaults['is_admin'] ? admin::transactions_reset($defaults) : lost::index($defaults),
diff --git a/src/controllers/admin.php b/src/controllers/admin.php
index f94c1c1..bd8a793 100644
--- a/src/controllers/admin.php
+++ b/src/controllers/admin.php
@@ -1,6 +1,7 @@
 <?php
 namespace app\controllers;
 
+use app\models\categories;
 use app\models\emails;
 use app\models\transactions;
 use app\models\users;
@@ -39,19 +40,119 @@ class admin
         ]));
     }
 
-    public static function orders($defaults)
+    public static function products($defaults)
     {
         echo $GLOBALS['twig']->render('lib/pages/index.twig', array_merge($defaults, [
-            'child_template' => 'admin/orders.twig',
-            'page_title'     => 'Orders',
+            'child_template' => 'admin/products/index.twig',
+            'page_title'     => 'Products',
+            'categories'     => categories::getTree(),
             'breadcrumbs'    => [
                 [
                     'url'   => '/admin',
                     'title' => 'Admin',
                 ],
                 [
-                    'url'   => '/admin/orders',
-                    'title' => 'Orders',
+                    'url'   => '/admin/products',
+                    'title' => 'Products',
+                ],
+            ],
+        ]));
+    }
+
+    public static function categories($defaults)
+    {
+        echo $GLOBALS['twig']->render('lib/pages/index.twig', array_merge($defaults, [
+            'child_template' => 'admin/categories/index.twig',
+            'page_title'     => 'Categories',
+            'categories'     => categories::getTree(),
+            'breadcrumbs'    => [
+                [
+                    'url'   => '/admin',
+                    'title' => 'Admin',
+                ],
+                [
+                    'url'   => '/admin/categories',
+                    'title' => 'Categories',
+                ],
+            ],
+        ]));
+    }
+
+    public static function categories_add($defaults)
+    {
+        if ($_SERVER['REQUEST_METHOD'] == 'POST') {
+            $parent_id = $_POST['parent_id'] ?? null;
+            $label     = $_POST['label'] ?? null;
+            $value     = $_POST['value'] ?? null;
+            if (! $label || ! $value) {
+                $_SESSION['error'] = 'Title and slug are required fields.';
+                header('Location: /admin/categories/add');
+                exit;
+            }
+            categories::add($label, $value, $parent_id);
+            $_SESSION['success'] = 'Category added successfully.';
+            header('Location: /admin/categories/add');
+            exit;
+        }
+        echo $GLOBALS['twig']->render('lib/pages/index.twig', array_merge($defaults, [
+            'child_template' => 'admin/categories/add.twig',
+            'page_title'     => 'Add a Category',
+            'categories'     => categories::getOptions(),
+            'breadcrumbs'    => [
+                [
+                    'url'   => '/admin',
+                    'title' => 'Admin',
+                ],
+                [
+                    'url'   => '/admin/products',
+                    'title' => 'Products',
+                ],
+                [
+                    'url'   => null,
+                    'title' => 'Add Category',
+                ],
+            ],
+        ]));
+    }
+
+    public static function categories_edit($defaults, $cat_id)
+    {
+        if ($_SERVER['REQUEST_METHOD'] == 'POST') {
+            $parent_id = $_POST['parent_id'] ?? null;
+            $label     = $_POST['label'] ?? null;
+            $value     = $_POST['value'] ?? null;
+            if (! $label || ! $value) {
+                $_SESSION['error'] = 'Title and slug are required fields.';
+                header('Location: /admin/categories/edit/' . $cat_id);
+                exit;
+            }
+            if ($cat_id == $parent_id) {
+                $_SESSION['error'] = 'A category cannot be its own parent.';
+                header('Location: /admin/categories/edit/' . $cat_id);
+                exit;
+            }
+            categories::updateById($cat_id, $label, $value, $parent_id);
+            $_SESSION['success'] = 'Category updated successfully.';
+            header('Location: /admin/categories/edit/' . $cat_id);
+            exit;
+        }
+        echo $GLOBALS['twig']->render('lib/pages/index.twig', array_merge($defaults, [
+            'child_template' => 'admin/categories/edit.twig',
+            'page_title'     => 'Edit Category',
+            'category'       => categories::getById($cat_id),
+            'categories'     => categories::getOptions(),
+            'breadcrumbs'    => [
+                [
+                    'url'   => '/admin',
+                    'title' => 'Admin',
+                ],
+                [
+                    'url'   => '/admin/categories',
+                    'title' => 'Categories',
+                ],
+                [
+                    'url'   => null,
+                    'title' => 'Edit',
                 ],
             ],
         ]));
diff --git a/src/controllers/magic_link.php b/src/controllers/magic_link.php
index 95add7c..cab07dd 100644
--- a/src/controllers/magic_link.php
+++ b/src/controllers/magic_link.php
@@ -21,7 +21,7 @@ class magic_link
                     $user = $link['user_id'] ? users::getById($link['user_id']) : users::getByEmail($link['email']);
                     if ($user) { // this email is registered or associated with a user
                         $user_replacing = users::getByReplaceEmailToken($link['token']);
-                        if ($user_replacing) { // user is replacing their email
+                        if ($user_replacing && $user_replacing['id'] == $link['user_id']) { // user is replacing their email
                             users::updateEmailById($user_replacing['id'], $link['email']);
                             $_SESSION['user_email'] = $link['email'];
                             $_SESSION['user_id']    = $user_replacing['id'];
@@ -66,7 +66,7 @@ class magic_link
                 $user = $link['user_id'] ? users::getById($link['user_id']) : users::getByEmail($link['email']);
                 if ($user) { // this email is registered or is associated with a user
                     $user_replacing = users::getByReplaceEmailToken($token);
-                    if ($user_replacing) { // user is replacing their email
+                    if ($user_replacing && $user_replacing['id'] == $link['user_id']) { // user is replacing their email
                         users::updateEmailById($user_replacing['id'], $link['email']);
                         $_SESSION['user_email'] = $link['email'];
                         $_SESSION['user_id']    = $user_replacing['id'];
diff --git a/src/models/categories.php b/src/models/categories.php
new file mode 100644
index 0000000..5d30a96
--- /dev/null
+++ b/src/models/categories.php
@@ -0,0 +1,96 @@
+<?php
+namespace app\models;
+
+use app\app;
+
+class categories
+{
+    public static function init()
+    {
+        app::$db->exec("CREATE TABLE IF NOT EXISTS categories (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            parent_id INTEGER,
+            label TEXT UNIQUE NOT NULL,
+            value TEXT UNIQUE NOT NULL,
+            FOREIGN KEY (parent_id) REFERENCES categories(id)
+        );");
+    }
+
+    public static function add($label, $value, $parent_id = null): string
+    {
+        $stmt = app::$db->prepare("INSERT INTO categories (label, value, parent_id) VALUES (:label, :value, :parent_id)");
+        $stmt->bindParam(':label', $label);
+        $stmt->bindParam(':value', $value);
+        $stmt->bindParam(':parent_id', $parent_id);
+        $stmt->execute();
+        return app::$db->lastInsertId();
+    }
+
+    public static function updateById($id, $label, $value, $parent_id = null)
+    {
+        $stmt = app::$db->prepare("UPDATE categories SET label = :label, value = :value, parent_id = :parent_id WHERE id = :id");
+        $stmt->bindParam(':id', $id, \PDO::PARAM_INT);
+        $stmt->bindParam(':label', $label);
+        $stmt->bindParam(':value', $value);
+        $stmt->bindParam(':parent_id', $parent_id);
+        return $stmt->execute();
+    }
+
+    public static function getById($id)
+    {
+        $stmt = app::$db->prepare("SELECT * FROM categories WHERE id = :id");
+        $stmt->bindParam(':id', $id, \PDO::PARAM_INT);
+        $stmt->execute();
+        return $stmt->fetch(\PDO::FETCH_ASSOC);
+    }
+
+    public static function getTree(): array
+    {
+        $stmt       = app::$db->query("SELECT * FROM categories");
+        $categories = $stmt->fetchAll(\PDO::FETCH_ASSOC);
+        $tree       = [];
+        $map        = [];
+        foreach ($categories as &$category) {
+            $category['children'] = [];
+            $map[$category['id']] = &$category;
+        }
+        foreach ($categories as &$category) {
+            if (! $category['parent_id']) {
+                $tree[] = &$category;
+            } else {
+                if (isset($map[$category['parent_id']])) {
+                    $map[$category['parent_id']]['children'][] = &$category;
+                }
+            }
+        }
+        return $tree;
+    }
+
+    public static function getOptions(): array
+    {
+        $stmt       = app::$db->query("SELECT * FROM categories");
+        $categories = $stmt->fetchAll(\PDO::FETCH_ASSOC);
+
+        $flattened = [];
+        foreach ($categories as $category) {
+            $depth   = 0;
+            $current = $category;
+            while ($current['parent_id'] !== null) {
+                $depth++;
+                $current = array_filter($categories, function ($cat) use ($current) {
+                    return $cat['id'] === $current['parent_id'];
+                });
+                $current = reset($current);
+                if (! $current) {
+                    break;
+                }
+            }
+            $flattened[] = [
+                'label' => str_repeat('-', $depth) . ' ' . $category['label'],
+                'value' => $category['id'],
+            ];
+        }
+        return $flattened;
+    }
+
+}
diff --git a/src/scripts/init_db.php b/src/scripts/init_db.php
index e9bb9d2..b0996d5 100644
--- a/src/scripts/init_db.php
+++ b/src/scripts/init_db.php
@@ -16,6 +16,7 @@ app::init_db();
 use app\models\addresses;
 use app\models\carts;
 use app\models\cart_items;
+use app\models\categories;
 use app\models\emails;
 use app\models\invoices;
 use app\models\magic_links;
@@ -33,6 +34,7 @@ use app\models\user_settings;
 addresses::init();
 carts::init();
 cart_items::init();
+categories::init();
 emails::init();
 invoices::init();
 magic_links::init();
diff --git a/src/views/admin/categories/add.twig b/src/views/admin/categories/add.twig
new file mode 100644
index 0000000..c80397d
--- /dev/null
+++ b/src/views/admin/categories/add.twig
@@ -0,0 +1,9 @@
+<section class="flex flex-col gap-4">
+    {% include 'lib/alert.twig' %}
+    <form action="/admin/categories/add" method="POST" class="flex flex-col gap-4">
+        {% include 'lib/forms/category.twig' %}
+        {% include 'lib/buttons/submit.twig' with { 
+            label: 'Add Category' 
+        } %}
+    </form>
+</section>
diff --git a/src/views/admin/categories/edit.twig b/src/views/admin/categories/edit.twig
new file mode 100644
index 0000000..db01eeb
--- /dev/null
+++ b/src/views/admin/categories/edit.twig
@@ -0,0 +1,12 @@
+{% include 'lib/alert.twig' %}
+
+<form action="/admin/categories/edit/{{ category.id }}" method="post" class="flex flex-col gap-2">
+    {% include 'lib/forms/category.twig' with {
+        value: category.value,
+        label: category.label,
+        parent_id: category.parent_id
+    } %}
+    {% include 'lib/buttons/submit.twig' with { 
+        label: 'Save Category' 
+    } %}
+</form>
diff --git a/src/views/admin/categories/index.twig b/src/views/admin/categories/index.twig
new file mode 100644
index 0000000..d695586
--- /dev/null
+++ b/src/views/admin/categories/index.twig
@@ -0,0 +1,70 @@
+<section class="flex flex-col gap-4">
+    {% include 'lib/alert.twig' %}
+
+    <h3 class="text-2xl font-semibold">
+        Categories
+    </h3>
+    <a href="/admin/categories/add">
+        {% include 'lib/buttons/primary.twig' with {
+            label: 'Create a Category'
+        } %}
+    </a>
+    <table class="min-w-full">
+        <tr>
+            <th class="py-2">
+                Category ID
+            </th>
+            <th class="py-2">
+                Title
+            </th>
+            <th class="py-2">
+                Slug
+            </th>
+            <th class="py-2">
+                Action
+            </th>
+        </tr>
+    </thead>
+    <tbody>
+        {% macro renderCategory(category, depth) %}
+            <tr>
+                <td class="border px-4 py-2">
+                    {{ category.id }}
+                </td>
+                <td class="border px-4 py-2">
+                    {% if depth > 0 %}
+                        {% for i in 1..depth %}
+                            -
+                        {% endfor %}
+                    {% endif %}
+                    {{ category.label }}
+                </td>
+                <td class="border px-4 py-2">
+                    {{ category.value }}
+                </td>
+                <td class="border px-4 py-2">
+                    <a href="/admin/categories/edit/{{ category.id }}">
+                        Edit
+                    </a>
+                </td>
+            </tr>
+            {% if category.children is defined and category.children is not empty %}
+                {% for child in category.children %}
+                    {{ _self.renderCategory(child, depth + 1) }}
+                {% endfor %}
+            {% endif %}
+        {% endmacro %}
+
+        {% if categories %}
+            {% for category in categories %}
+                {{ _self.renderCategory(category, 0) }}
+            {% endfor %}
+        {% else %}
+            <tr>
+                <td class="border px-4 py-2" colspan="4">
+                    No categories yet.
+                </td>
+            </tr>
+        {% endif %}
+    </tbody>
+</table></section>
\ No newline at end of file
diff --git a/src/views/admin/index.twig b/src/views/admin/index.twig
index 7f6a083..a8d22e6 100644
--- a/src/views/admin/index.twig
+++ b/src/views/admin/index.twig
@@ -5,6 +5,12 @@
     <a href="/admin/users">
         Users
     </a>
+    <a href="/admin/products">
+        Products
+    </a>
+    <a href="/admin/categories">
+        Categories
+    </a>
     <a href="/admin/orders">
         Orders
     </a>
diff --git a/src/views/admin/products/index.twig b/src/views/admin/products/index.twig
new file mode 100644
index 0000000..90e213e
--- /dev/null
+++ b/src/views/admin/products/index.twig
@@ -0,0 +1,62 @@
+<section class="flex flex-col gap-4">
+    {% include 'lib/alert.twig' %}
+
+    <h3 class="text-2xl font-semibold">
+        Categories
+    </h3>
+    <a href="/admin/categories/add">
+        {% include 'lib/buttons/primary.twig' with {
+            label: 'Create a Category'
+        } %}
+    </a>
+    <table class="min-w-full">
+        <tr>
+            <th class="py-2">
+                Category ID
+            </th>
+            <th class="py-2">
+                Title
+            </th>
+            <th class="py-2">
+                Slug
+            </th>
+        </tr>
+    </thead>
+    <tbody>
+        {% macro renderCategory(category, depth) %}
+            <tr>
+                <td class="border px-4 py-2">
+                    {{ category.id }}
+                </td>
+                <td class="border px-4 py-2">
+                    {% if depth > 0 %}
+                        {% for i in 1..depth %}
+                            -
+                        {% endfor %}
+                    {% endif %}
+                    {{ category.label }}
+                </td>
+                <td class="border px-4 py-2">
+                    {{ category.value }}
+                </td>
+            </tr>
+            {% if category.children is defined and category.children is not empty %}
+                {% for child in category.children %}
+                    {{ _self.renderCategory(child, depth + 1) }}
+                {% endfor %}
+            {% endif %}
+        {% endmacro %}
+
+        {% if categories is not empty %}
+            {% for category in categories %}
+                {{ _self.renderCategory(category, 0) }}
+            {% endfor %}
+        {% else %}
+            <tr>
+                <td class="border px-4 py-2" colspan="3">
+                    No categories yet.
+                </td>
+            </tr>
+        {% endif %}
+    </tbody>
+</table></section>
\ No newline at end of file
diff --git a/src/views/admin/transactions/add.twig b/src/views/admin/transactions/add.twig
index 309ea35..1662a9f 100644
--- a/src/views/admin/transactions/add.twig
+++ b/src/views/admin/transactions/add.twig
@@ -13,8 +13,8 @@
             name: 'currency', 
             label: 'Currency',
             options: [
-                { 'value': 'sats', 'text': 'Sats' },
-                { 'value': 'cents', 'text': 'Cents' }
+                { 'value': 'sats', 'label': 'Sats' },
+                { 'value': 'cents', 'label': 'Cents' }
             ],
             required: true
         } %}
diff --git a/src/views/lib/forms/category.twig b/src/views/lib/forms/category.twig
new file mode 100644
index 0000000..6a55b3e
--- /dev/null
+++ b/src/views/lib/forms/category.twig
@@ -0,0 +1,19 @@
+{% include 'lib/inputs/text.twig' with { 
+    name: 'label', 
+    label: 'Category Title', 
+    placeholder: 'Enter category title',
+    value: label
+} %}
+{% include 'lib/inputs/text.twig' with { 
+    name: 'value', 
+    label: 'Category Slug', 
+    placeholder: 'Enter category slug',
+    value: value
+} %}
+{% include 'lib/inputs/select.twig' with { 
+    name: 'parent_id', 
+    label: 'Parent Category', 
+    options: categories,
+    value: parent_id,
+    no_option: { 'label': '-- None --', 'value': null}
+} %}
diff --git a/src/views/lib/inputs/select.twig b/src/views/lib/inputs/select.twig
index c1a867d..65a697b 100644
--- a/src/views/lib/inputs/select.twig
+++ b/src/views/lib/inputs/select.twig
@@ -2,9 +2,14 @@
     {{ label }}
 </label>
 <select id="{{ id }}" name="{{ name }}" class="border rounded-lg p-2 w-full" {% if required %} required {% endif %}>
+    {% if no_option is defined %}
+        <option value="{{ no_option.value }}">
+            {{ no_option.label }}
+        </option>
+    {% endif %}
     {% for option in options %}
         <option value="{{ option.value }}" {% if option.value == value %} selected {% endif %}>
-            {{ option.text }}
+            {{ option.label }}
         </option>
     {% endfor %}
 </select>