diff --git a/README.md b/README.md
index 5a83916..016b758 100644
--- a/README.md
+++ b/README.md
@@ -53,8 +53,8 @@ This project is a full-stack web application featuring:
 - 🗄️ **Database CRUD Operations** - Full Create, Read, Update, Delete functionality
 - 🛠️ **Admin Panel** - Manage tables, columns, and data through a beautiful UI
 - 📊 **Table Manager** - Create and drop tables with visual column definition
-- 🔧 **Column Manager** - Add, modify, and drop columns from existing tables
-- 🔒 **Constraint Manager** - Add and manage UNIQUE and CHECK constraints (fully implemented)
+- 🔧 **Column Manager** - Add, modify, and drop columns with DEFAULT values and NOT NULL support
+- 🔒 **Constraint Manager** - Add and manage UNIQUE, CHECK, and PRIMARY KEY constraints (fully implemented)
 - 📊 **SQL Query Interface** - Execute custom queries with safety validation
 - 🔒 **JWT Authentication** with secure session management
 - 📦 **DrizzleORM** - Support for PostgreSQL, MySQL, and SQLite
@@ -73,8 +73,8 @@ This is a **PostgreSQL database administration panel** that provides:
 - 🔒 **Secure authentication** with bcrypt password hashing and JWT sessions
 - 📊 **Database viewing** - Browse tables, view data, and explore schema
 - 🛠️ **Table management** - Create and drop tables through intuitive UI
-- 🔧 **Column management** - Add, modify, and drop columns with type selection
-- 🔐 **Constraint management** - Add UNIQUE and CHECK constraints for data validation
+- 🔧 **Column management** - Add, modify, and drop columns with DEFAULT values and NOT NULL support
+- 🔐 **Constraint management** - Add UNIQUE, CHECK, and PRIMARY KEY constraints for data validation
 - 🔍 **SQL query interface** - Execute SELECT queries safely with result display
 - 🐳 **All-in-one Docker image** - PostgreSQL 15 and admin UI in one container
 - ⚡ **Production-ready** - Deploy to Caprover, Docker, or any cloud platform
diff --git a/ROADMAP.md b/ROADMAP.md
index 860fa63..eb3ab19 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -65,9 +65,9 @@ See `src/config/features.json` for the complete feature configuration.
     - [x] ✅ Add constraint listing endpoint
     - [x] ✅ Add constraint creation/deletion endpoints
     - [x] ✅ Build constraints management UI
-    - [ ] Add PRIMARY KEY constraint support
-    - [ ] Add DEFAULT value management
-    - [ ] Add NOT NULL constraint management
+    - [x] Add PRIMARY KEY constraint support ✅ **COMPLETED**
+    - [x] Add DEFAULT value management ✅ **COMPLETED**
+    - [x] Add NOT NULL constraint management ✅ **COMPLETED**
   - [ ] Build query builder interface
   - [ ] Add foreign key relationship management
   - [ ] Implement index management UI
diff --git a/TESTING.md b/TESTING.md
index 03b4537..76fb3f6 100644
--- a/TESTING.md
+++ b/TESTING.md
@@ -35,11 +35,16 @@ Tests for the Column Management API endpoints (`/api/admin/column-manage`):
 - ✅ Validates all required fields (tableName, columnName, dataType)
 - ✅ Rejects invalid table names
 - ✅ Rejects invalid column names
+- ✅ Accepts columns with NOT NULL constraint
+- ✅ Accepts columns with DEFAULT values
+- ✅ Accepts columns with both DEFAULT and NOT NULL
 
 **Modify Column Tests:**
 - ✅ Requires authentication
 - ✅ Validates required fields
 - ✅ Rejects invalid identifiers
+- ✅ Accepts setting NOT NULL constraint
+- ✅ Accepts dropping NOT NULL constraint
 
 **Drop Column Tests:**
 - ✅ Requires authentication
@@ -148,10 +153,10 @@ All tests verify that:
 |---------|-----------|----------|----------------|------------|-------------|
 | Feature Config | - | - | - | 40 | 40 |
 | Table Manager | 7 | 2 (2 skipped) | 3 | - | 12 |
-| Column Manager | 9 | 2 (2 skipped) | 3 | - | 14 |
-| Constraint Manager | 14 | 3 (3 skipped) | 4 | 4 | 25 |
+| Column Manager | 12 | 2 (2 skipped) | 3 | - | 17 |
+| Constraint Manager | 15 | 3 (3 skipped) | 4 | 5 | 27 |
 | Admin Dashboard | - | 3 | 3 | - | 6 |
-| **Total** | **30** | **10** | **16** | **44** | **100** |
+| **Total** | **34** | **10** | **16** | **45** | **105** |
 
 ## Feature: Constraint Management Tests
 
@@ -169,6 +174,7 @@ Tests for the Constraint Management API endpoints (`/api/admin/constraints`):
 - ✅ Rejects add without authentication
 - ✅ Rejects add without required fields
 - ✅ Rejects add with invalid table name
+- ✅ Rejects PRIMARY KEY constraint without column name
 - ✅ Rejects UNIQUE constraint without column name
 - ✅ Rejects CHECK constraint without expression
 - ✅ Rejects CHECK constraint with dangerous expression (SQL injection prevention)
@@ -184,7 +190,7 @@ Tests for the Constraint Management API endpoints (`/api/admin/constraints`):
 - SQL injection prevention
 - Authentication/authorization
 - Error handling for all CRUD operations
-- Support for UNIQUE and CHECK constraints
+- Support for PRIMARY KEY, UNIQUE and CHECK constraints
 
 ### End-to-End Tests (Playwright UI Tests)
 
@@ -213,6 +219,7 @@ Tests for the constraint types configuration:
 **Constraint Types Tests:**
 - ✅ Returns array of constraint types
 - ✅ Validates constraint type properties
+- ✅ Includes PRIMARY KEY constraint type with correct flags
 - ✅ Includes UNIQUE constraint type with correct flags
 - ✅ Includes CHECK constraint type with correct flags
 
diff --git a/src/app/api/admin/constraints/route.ts b/src/app/api/admin/constraints/route.ts
index 6a6d654..4443206 100644
--- a/src/app/api/admin/constraints/route.ts
+++ b/src/app/api/admin/constraints/route.ts
@@ -69,7 +69,7 @@ export async function GET(request: Request) {
         ON tc.constraint_name = cc.constraint_name
       WHERE tc.table_schema = 'public'
         AND tc.table_name = ${tableName}
-        AND tc.constraint_type IN ('UNIQUE', 'CHECK')
+        AND tc.constraint_type IN ('PRIMARY KEY', 'UNIQUE', 'CHECK')
       ORDER BY tc.constraint_name
     `);
 
@@ -133,7 +133,15 @@ export async function POST(request: Request) {
 
     let alterQuery = '';
 
-    if (constraintType === 'UNIQUE') {
+    if (constraintType === 'PRIMARY KEY') {
+      if (!columnName) {
+        return NextResponse.json(
+          { error: 'Column name is required for PRIMARY KEY constraint' },
+          { status: 400 },
+        );
+      }
+      alterQuery = `ALTER TABLE "${tableName}" ADD CONSTRAINT "${constraintName}" PRIMARY KEY ("${columnName}")`;
+    } else if (constraintType === 'UNIQUE') {
       if (!columnName) {
         return NextResponse.json(
           { error: 'Column name is required for UNIQUE constraint' },
@@ -170,7 +178,7 @@ export async function POST(request: Request) {
       alterQuery = `ALTER TABLE "${tableName}" ADD CONSTRAINT "${constraintName}" CHECK (${checkExpression})`;
     } else {
       return NextResponse.json(
-        { error: 'Unsupported constraint type. Supported types: UNIQUE, CHECK' },
+        { error: 'Unsupported constraint type. Supported types: PRIMARY KEY, UNIQUE, CHECK' },
         { status: 400 },
       );
     }
diff --git a/src/config/features.json b/src/config/features.json
index 4ba7643..732b428 100644
--- a/src/config/features.json
+++ b/src/config/features.json
@@ -107,6 +107,12 @@
     }
   ],
   "constraintTypes": [
+    {
+      "name": "PRIMARY KEY",
+      "description": "Unique identifier for table rows",
+      "requiresColumn": true,
+      "requiresExpression": false
+    },
     {
       "name": "UNIQUE",
       "description": "Ensure column values are unique",
diff --git a/src/utils/featureConfig.test.ts b/src/utils/featureConfig.test.ts
index cb06634..afe0cf5 100644
--- a/src/utils/featureConfig.test.ts
+++ b/src/utils/featureConfig.test.ts
@@ -280,6 +280,15 @@ describe('FeatureConfig', () => {
       });
     });
 
+    it('should include PRIMARY KEY constraint type', () => {
+      const constraintTypes = getConstraintTypes();
+      const primaryKeyConstraint = constraintTypes.find(ct => ct.name === 'PRIMARY KEY');
+      
+      expect(primaryKeyConstraint).toBeDefined();
+      expect(primaryKeyConstraint?.requiresColumn).toBe(true);
+      expect(primaryKeyConstraint?.requiresExpression).toBe(false);
+    });
+
     it('should include UNIQUE constraint type', () => {
       const constraintTypes = getConstraintTypes();
       const uniqueConstraint = constraintTypes.find(ct => ct.name === 'UNIQUE');
diff --git a/tests/integration/ColumnManager.spec.ts b/tests/integration/ColumnManager.spec.ts
index 4df9f2d..c9008a2 100644
--- a/tests/integration/ColumnManager.spec.ts
+++ b/tests/integration/ColumnManager.spec.ts
@@ -48,6 +48,46 @@ test.describe('Column Manager', () => {
 
       expect([400, 401]).toContain(response.status());
     });
+
+    test('should accept add column with NOT NULL constraint', async ({ page }) => {
+      const response = await page.request.post('/api/admin/column-manage', {
+        data: {
+          tableName: 'test_table',
+          columnName: 'test_column',
+          dataType: 'INTEGER',
+          nullable: false,
+        },
+      });
+
+      expect([400, 401, 404, 500]).toContain(response.status());
+    });
+
+    test('should accept add column with DEFAULT value', async ({ page }) => {
+      const response = await page.request.post('/api/admin/column-manage', {
+        data: {
+          tableName: 'test_table',
+          columnName: 'test_column',
+          dataType: 'INTEGER',
+          defaultValue: 0,
+        },
+      });
+
+      expect([400, 401, 404, 500]).toContain(response.status());
+    });
+
+    test('should accept add column with DEFAULT value and NOT NULL', async ({ page }) => {
+      const response = await page.request.post('/api/admin/column-manage', {
+        data: {
+          tableName: 'test_table',
+          columnName: 'test_column',
+          dataType: 'VARCHAR',
+          nullable: false,
+          defaultValue: 'default_value',
+        },
+      });
+
+      expect([400, 401, 404, 500]).toContain(response.status());
+    });
   });
 
   test.describe('Modify Column API', () => {
@@ -84,6 +124,30 @@ test.describe('Column Manager', () => {
 
       expect([400, 401]).toContain(response.status());
     });
+
+    test('should accept modify column to set NOT NULL', async ({ page }) => {
+      const response = await page.request.put('/api/admin/column-manage', {
+        data: {
+          tableName: 'test_table',
+          columnName: 'test_column',
+          nullable: false,
+        },
+      });
+
+      expect([400, 401, 404, 500]).toContain(response.status());
+    });
+
+    test('should accept modify column to drop NOT NULL', async ({ page }) => {
+      const response = await page.request.put('/api/admin/column-manage', {
+        data: {
+          tableName: 'test_table',
+          columnName: 'test_column',
+          nullable: true,
+        },
+      });
+
+      expect([400, 401, 404, 500]).toContain(response.status());
+    });
   });
 
   test.describe('Drop Column API', () => {
diff --git a/tests/integration/ConstraintManager.spec.ts b/tests/integration/ConstraintManager.spec.ts
index cfd6dcf..a8f15ad 100644
--- a/tests/integration/ConstraintManager.spec.ts
+++ b/tests/integration/ConstraintManager.spec.ts
@@ -58,6 +58,18 @@ test.describe('Constraint Manager', () => {
       expect([400, 401]).toContain(response.status());
     });
 
+    test('should reject PRIMARY KEY constraint without column name', async ({ page }) => {
+      const response = await page.request.post('/api/admin/constraints', {
+        data: {
+          tableName: 'test_table',
+          constraintName: 'test_pk',
+          constraintType: 'PRIMARY KEY',
+        },
+      });
+      
+      expect([400, 401]).toContain(response.status());
+    });
+
     test('should reject UNIQUE constraint without column name', async ({ page }) => {
       const response = await page.request.post('/api/admin/constraints', {
         data: {