diff --git a/api/user-cards.js b/api/user-cards.js
new file mode 100644
index 0000000..5fbb920
--- /dev/null
+++ b/api/user-cards.js
@@ -0,0 +1,429 @@
+import { NextResponse } from 'next/server';
+import { sql } from '@vercel/postgres';
+import { verifyToken } from './setup-auth.js';
+
+// GET /api/user-cards - Get user's cards with optional filters
+export async function GET(request) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { searchParams } = new URL(request.url);
+    const game = searchParams.get('game');
+    const rarity = searchParams.get('rarity');
+    const status = searchParams.get('status');
+    const search = searchParams.get('search');
+
+    let query = `
+      SELECT 
+        uc.id,
+        uc.user_id,
+        uc.card_id,
+        uc.status,
+        uc.quantity,
+        uc.condition,
+        uc.notes,
+        uc.acquired_date,
+        uc.acquired_price,
+        uc.acquired_from,
+        uc.created_at,
+        uc.updated_at,
+        c.name,
+        c.set_name,
+        c.set_code,
+        c.card_number,
+        c.rarity,
+        c.game,
+        c.card_type,
+        c.mana_cost,
+        c.cmc,
+        c.colors,
+        c.oracle_text,
+        c.power,
+        c.toughness,
+        c.image_url,
+        c.stock_image_url,
+        c.current_price,
+        c.market_price,
+        c.verified,
+        c.created_at as card_created_at,
+        c.updated_at as card_updated_at
+      FROM user_cards uc
+      JOIN cards c ON uc.card_id = c.id
+      WHERE uc.user_id = $1
+    `;
+
+    const params = [user.id];
+    let paramIndex = 2;
+
+    if (game) {
+      query += ` AND c.game = $${paramIndex}`;
+      params.push(game);
+      paramIndex++;
+    }
+
+    if (rarity) {
+      query += ` AND c.rarity = $${paramIndex}`;
+      params.push(rarity);
+      paramIndex++;
+    }
+
+    if (status && status !== 'all') {
+      query += ` AND uc.status = $${paramIndex}`;
+      params.push(status);
+      paramIndex++;
+    }
+
+    if (search) {
+      query += ` AND (c.name ILIKE $${paramIndex} OR c.set_name ILIKE $${paramIndex})`;
+      params.push(`%${search}%`);
+      paramIndex++;
+    }
+
+    query += ` ORDER BY uc.created_at DESC`;
+
+    const result = await sql.query(query, params);
+
+    const userCards = result.rows.map(row => ({
+      id: row.id,
+      userId: row.user_id,
+      cardId: row.card_id,
+      status: row.status,
+      quantity: row.quantity,
+      condition: row.condition,
+      notes: row.notes,
+      acquiredDate: row.acquired_date,
+      acquiredPrice: row.acquired_price,
+      acquiredFrom: row.acquired_from,
+      createdAt: row.created_at,
+      updatedAt: row.updated_at,
+      card: {
+        id: row.card_id,
+        name: row.name,
+        set_name: row.set_name,
+        set_code: row.set_code,
+        card_number: row.card_number,
+        rarity: row.rarity,
+        game: row.game,
+        card_type: row.card_type,
+        mana_cost: row.mana_cost,
+        cmc: row.cmc,
+        colors: row.colors ? JSON.parse(row.colors) : [],
+        oracle_text: row.oracle_text,
+        power: row.power,
+        toughness: row.toughness,
+        image_url: row.image_url,
+        stock_image_url: row.stock_image_url,
+        current_price: row.current_price,
+        market_price: row.market_price,
+        verified: row.verified,
+        createdAt: row.card_created_at,
+        updatedAt: row.card_updated_at,
+      }
+    }));
+
+    return NextResponse.json({
+      success: true,
+      data: userCards,
+      message: `Found ${userCards.length} cards`
+    });
+
+  } catch (error) {
+    console.error('Error fetching user cards:', error);
+    return NextResponse.json(
+      { error: 'Failed to fetch user cards' },
+      { status: 500 }
+    );
+  }
+}
+
+// POST /api/user-cards - Add card to user collection
+export async function POST(request) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const body = await request.json();
+    const {
+      cardId,
+      status = 'owned',
+      quantity = 1,
+      condition,
+      notes,
+      acquiredDate,
+      acquiredPrice,
+      acquiredFrom,
+      collectionIds = [],
+      deckIds = []
+    } = body;
+
+    if (!cardId) {
+      return NextResponse.json(
+        { error: 'Card ID is required' },
+        { status: 400 }
+      );
+    }
+
+    // Check if card exists
+    const cardResult = await sql.query(
+      'SELECT id FROM cards WHERE id = $1',
+      [cardId]
+    );
+
+    if (cardResult.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found' },
+        { status: 404 }
+      );
+    }
+
+    // Check if user already has this card
+    const existingResult = await sql.query(
+      'SELECT id FROM user_cards WHERE user_id = $1 AND card_id = $2',
+      [user.id, cardId]
+    );
+
+    if (existingResult.rows.length > 0) {
+      return NextResponse.json(
+        { error: 'Card already in collection' },
+        { status: 409 }
+      );
+    }
+
+    // Add card to user collection
+    const result = await sql.query(
+      `INSERT INTO user_cards (
+        user_id, card_id, status, quantity, condition, notes,
+        acquired_date, acquired_price, acquired_from, created_at, updated_at
+      ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, NOW(), NOW())
+      RETURNING *`,
+      [
+        user.id, cardId, status, quantity, condition, notes,
+        acquiredDate, acquiredPrice, acquiredFrom
+      ]
+    );
+
+    const userCard = result.rows[0];
+
+    // Add to collections if specified
+    if (collectionIds.length > 0) {
+      for (const collectionId of collectionIds) {
+        await sql.query(
+          'INSERT INTO collection_cards (collection_id, user_card_id) VALUES ($1, $2)',
+          [collectionId, userCard.id]
+        );
+      }
+    }
+
+    // Add to decks if specified
+    if (deckIds.length > 0) {
+      for (const deckId of deckIds) {
+        await sql.query(
+          'INSERT INTO deck_cards (deck_id, user_card_id, quantity, board) VALUES ($1, $2, $3, $4)',
+          [deckId, userCard.id, quantity, 'mainboard']
+        );
+      }
+    }
+
+    return NextResponse.json({
+      success: true,
+      data: {
+        id: userCard.id,
+        userId: userCard.user_id,
+        cardId: userCard.card_id,
+        status: userCard.status,
+        quantity: userCard.quantity,
+        condition: userCard.condition,
+        notes: userCard.notes,
+        acquiredDate: userCard.acquired_date,
+        acquiredPrice: userCard.acquired_price,
+        acquiredFrom: userCard.acquired_from,
+        createdAt: userCard.created_at,
+        updatedAt: userCard.updated_at,
+      },
+      message: 'Card added to collection'
+    });
+
+  } catch (error) {
+    console.error('Error adding card to collection:', error);
+    return NextResponse.json(
+      { error: 'Failed to add card to collection' },
+      { status: 500 }
+    );
+  }
+}
+
+// PUT /api/user-cards/[id] - Update user card
+export async function PUT(request, { params }) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { id } = params;
+    const body = await request.json();
+
+    // Check if user owns this card
+    const ownershipResult = await sql.query(
+      'SELECT id FROM user_cards WHERE id = $1 AND user_id = $2',
+      [id, user.id]
+    );
+
+    if (ownershipResult.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found or not owned by user' },
+        { status: 404 }
+      );
+    }
+
+    // Build update query dynamically
+    const updateFields = [];
+    const updateValues = [];
+    let paramIndex = 1;
+
+    if (body.status !== undefined) {
+      updateFields.push(`status = $${paramIndex}`);
+      updateValues.push(body.status);
+      paramIndex++;
+    }
+
+    if (body.quantity !== undefined) {
+      updateFields.push(`quantity = $${paramIndex}`);
+      updateValues.push(body.quantity);
+      paramIndex++;
+    }
+
+    if (body.condition !== undefined) {
+      updateFields.push(`condition = $${paramIndex}`);
+      updateValues.push(body.condition);
+      paramIndex++;
+    }
+
+    if (body.notes !== undefined) {
+      updateFields.push(`notes = $${paramIndex}`);
+      updateValues.push(body.notes);
+      paramIndex++;
+    }
+
+    if (body.acquiredDate !== undefined) {
+      updateFields.push(`acquired_date = $${paramIndex}`);
+      updateValues.push(body.acquiredDate);
+      paramIndex++;
+    }
+
+    if (body.acquiredPrice !== undefined) {
+      updateFields.push(`acquired_price = $${paramIndex}`);
+      updateValues.push(body.acquiredPrice);
+      paramIndex++;
+    }
+
+    if (body.acquiredFrom !== undefined) {
+      updateFields.push(`acquired_from = $${paramIndex}`);
+      updateValues.push(body.acquiredFrom);
+      paramIndex++;
+    }
+
+    if (updateFields.length === 0) {
+      return NextResponse.json(
+        { error: 'No fields to update' },
+        { status: 400 }
+      );
+    }
+
+    updateFields.push(`updated_at = NOW()`);
+    updateValues.push(id);
+
+    const query = `
+      UPDATE user_cards 
+      SET ${updateFields.join(', ')}
+      WHERE id = $${paramIndex}
+      RETURNING *
+    `;
+
+    const result = await sql.query(query, updateValues);
+    const userCard = result.rows[0];
+
+    return NextResponse.json({
+      success: true,
+      data: {
+        id: userCard.id,
+        userId: userCard.user_id,
+        cardId: userCard.card_id,
+        status: userCard.status,
+        quantity: userCard.quantity,
+        condition: userCard.condition,
+        notes: userCard.notes,
+        acquiredDate: userCard.acquired_date,
+        acquiredPrice: userCard.acquired_price,
+        acquiredFrom: userCard.acquired_from,
+        createdAt: userCard.created_at,
+        updatedAt: userCard.updated_at,
+      },
+      message: 'Card updated successfully'
+    });
+
+  } catch (error) {
+    console.error('Error updating user card:', error);
+    return NextResponse.json(
+      { error: 'Failed to update card' },
+      { status: 500 }
+    );
+  }
+}
+
+// DELETE /api/user-cards/[id] - Delete user card
+export async function DELETE(request, { params }) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { id } = params;
+
+    // Check if user owns this card
+    const ownershipResult = await sql.query(
+      'SELECT id FROM user_cards WHERE id = $1 AND user_id = $2',
+      [id, user.id]
+    );
+
+    if (ownershipResult.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found or not owned by user' },
+        { status: 404 }
+      );
+    }
+
+    // Delete from collections and decks first
+    await sql.query('DELETE FROM collection_cards WHERE user_card_id = $1', [id]);
+    await sql.query('DELETE FROM deck_cards WHERE user_card_id = $1', [id]);
+
+    // Delete the user card
+    await sql.query('DELETE FROM user_cards WHERE id = $1', [id]);
+
+    return NextResponse.json({
+      success: true,
+      message: 'Card removed from collection'
+    });
+
+  } catch (error) {
+    console.error('Error deleting user card:', error);
+    return NextResponse.json(
+      { error: 'Failed to delete card' },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file
diff --git a/api/user-cards/[id].js b/api/user-cards/[id].js
new file mode 100644
index 0000000..22fb8d8
--- /dev/null
+++ b/api/user-cards/[id].js
@@ -0,0 +1,282 @@
+import { NextResponse } from 'next/server';
+import { sql } from '@vercel/postgres';
+import { verifyToken } from '../setup-auth.js';
+
+// GET /api/user-cards/[id] - Get single user card
+export async function GET(request, { params }) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { id } = params;
+
+    const result = await sql.query(
+      `SELECT 
+        uc.id,
+        uc.user_id,
+        uc.card_id,
+        uc.status,
+        uc.quantity,
+        uc.condition,
+        uc.notes,
+        uc.acquired_date,
+        uc.acquired_price,
+        uc.acquired_from,
+        uc.created_at,
+        uc.updated_at,
+        c.name,
+        c.set_name,
+        c.set_code,
+        c.card_number,
+        c.rarity,
+        c.game,
+        c.card_type,
+        c.mana_cost,
+        c.cmc,
+        c.colors,
+        c.oracle_text,
+        c.power,
+        c.toughness,
+        c.image_url,
+        c.stock_image_url,
+        c.current_price,
+        c.market_price,
+        c.verified,
+        c.created_at as card_created_at,
+        c.updated_at as card_updated_at
+      FROM user_cards uc
+      JOIN cards c ON uc.card_id = c.id
+      WHERE uc.id = $1 AND uc.user_id = $2`,
+      [id, user.id]
+    );
+
+    if (result.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found or not owned by user' },
+        { status: 404 }
+      );
+    }
+
+    const row = result.rows[0];
+    const userCard = {
+      id: row.id,
+      userId: row.user_id,
+      cardId: row.card_id,
+      status: row.status,
+      quantity: row.quantity,
+      condition: row.condition,
+      notes: row.notes,
+      acquiredDate: row.acquired_date,
+      acquiredPrice: row.acquired_price,
+      acquiredFrom: row.acquired_from,
+      createdAt: row.created_at,
+      updatedAt: row.updated_at,
+      card: {
+        id: row.card_id,
+        name: row.name,
+        set_name: row.set_name,
+        set_code: row.set_code,
+        card_number: row.card_number,
+        rarity: row.rarity,
+        game: row.game,
+        card_type: row.card_type,
+        mana_cost: row.mana_cost,
+        cmc: row.cmc,
+        colors: row.colors ? JSON.parse(row.colors) : [],
+        oracle_text: row.oracle_text,
+        power: row.power,
+        toughness: row.toughness,
+        image_url: row.image_url,
+        stock_image_url: row.stock_image_url,
+        current_price: row.current_price,
+        market_price: row.market_price,
+        verified: row.verified,
+        createdAt: row.card_created_at,
+        updatedAt: row.card_updated_at,
+      }
+    };
+
+    return NextResponse.json({
+      success: true,
+      data: userCard
+    });
+
+  } catch (error) {
+    console.error('Error fetching user card:', error);
+    return NextResponse.json(
+      { error: 'Failed to fetch user card' },
+      { status: 500 }
+    );
+  }
+}
+
+// PUT /api/user-cards/[id] - Update user card
+export async function PUT(request, { params }) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { id } = params;
+    const body = await request.json();
+
+    // Check if user owns this card
+    const ownershipResult = await sql.query(
+      'SELECT id FROM user_cards WHERE id = $1 AND user_id = $2',
+      [id, user.id]
+    );
+
+    if (ownershipResult.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found or not owned by user' },
+        { status: 404 }
+      );
+    }
+
+    // Build update query dynamically
+    const updateFields = [];
+    const updateValues = [];
+    let paramIndex = 1;
+
+    if (body.status !== undefined) {
+      updateFields.push(`status = $${paramIndex}`);
+      updateValues.push(body.status);
+      paramIndex++;
+    }
+
+    if (body.quantity !== undefined) {
+      updateFields.push(`quantity = $${paramIndex}`);
+      updateValues.push(body.quantity);
+      paramIndex++;
+    }
+
+    if (body.condition !== undefined) {
+      updateFields.push(`condition = $${paramIndex}`);
+      updateValues.push(body.condition);
+      paramIndex++;
+    }
+
+    if (body.notes !== undefined) {
+      updateFields.push(`notes = $${paramIndex}`);
+      updateValues.push(body.notes);
+      paramIndex++;
+    }
+
+    if (body.acquiredDate !== undefined) {
+      updateFields.push(`acquired_date = $${paramIndex}`);
+      updateValues.push(body.acquiredDate);
+      paramIndex++;
+    }
+
+    if (body.acquiredPrice !== undefined) {
+      updateFields.push(`acquired_price = $${paramIndex}`);
+      updateValues.push(body.acquiredPrice);
+      paramIndex++;
+    }
+
+    if (body.acquiredFrom !== undefined) {
+      updateFields.push(`acquired_from = $${paramIndex}`);
+      updateValues.push(body.acquiredFrom);
+      paramIndex++;
+    }
+
+    if (updateFields.length === 0) {
+      return NextResponse.json(
+        { error: 'No fields to update' },
+        { status: 400 }
+      );
+    }
+
+    updateFields.push(`updated_at = NOW()`);
+    updateValues.push(id);
+
+    const query = `
+      UPDATE user_cards 
+      SET ${updateFields.join(', ')}
+      WHERE id = $${paramIndex}
+      RETURNING *
+    `;
+
+    const result = await sql.query(query, updateValues);
+    const userCard = result.rows[0];
+
+    return NextResponse.json({
+      success: true,
+      data: {
+        id: userCard.id,
+        userId: userCard.user_id,
+        cardId: userCard.card_id,
+        status: userCard.status,
+        quantity: userCard.quantity,
+        condition: userCard.condition,
+        notes: userCard.notes,
+        acquiredDate: userCard.acquired_date,
+        acquiredPrice: userCard.acquired_price,
+        acquiredFrom: userCard.acquired_from,
+        createdAt: userCard.created_at,
+        updatedAt: userCard.updated_at,
+      },
+      message: 'Card updated successfully'
+    });
+
+  } catch (error) {
+    console.error('Error updating user card:', error);
+    return NextResponse.json(
+      { error: 'Failed to update card' },
+      { status: 500 }
+    );
+  }
+}
+
+// DELETE /api/user-cards/[id] - Delete user card
+export async function DELETE(request, { params }) {
+  try {
+    const token = request.headers.get('authorization')?.replace('Bearer ', '');
+    const user = await verifyToken(token);
+    
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const { id } = params;
+
+    // Check if user owns this card
+    const ownershipResult = await sql.query(
+      'SELECT id FROM user_cards WHERE id = $1 AND user_id = $2',
+      [id, user.id]
+    );
+
+    if (ownershipResult.rows.length === 0) {
+      return NextResponse.json(
+        { error: 'Card not found or not owned by user' },
+        { status: 404 }
+      );
+    }
+
+    // Delete from collections and decks first
+    await sql.query('DELETE FROM collection_cards WHERE user_card_id = $1', [id]);
+    await sql.query('DELETE FROM deck_cards WHERE user_card_id = $1', [id]);
+
+    // Delete the user card
+    await sql.query('DELETE FROM user_cards WHERE id = $1', [id]);
+
+    return NextResponse.json({
+      success: true,
+      message: 'Card removed from collection'
+    });
+
+  } catch (error) {
+    console.error('Error deleting user card:', error);
+    return NextResponse.json(
+      { error: 'Failed to delete card' },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file