diff --git a/README.md b/README.md
index c0577e1..f6357eb 100644
--- a/README.md
+++ b/README.md
@@ -85,11 +85,39 @@ Where columns are:
 4. Record Type (A, AAAA, MX, CNAME, TXT, etc.)
 5. Record Data (IP address, hostname, or other data depending on record type)
 
+## Domain Base Name Detection
+
+The application includes functionality to identify base domains from fully qualified domain names, including handling of multi-part TLDs like ".co.uk" or ".com.au".
+
+### Multi-Part TLD List
+
+The application uses a hardcoded list of common multi-part TLDs to correctly extract base domains (e.g., "example.co.uk" from "mail.example.co.uk").
+
+This list can be found in `main.py` as `MULTI_PART_TLDS`.
+
+### Updating the TLD List
+
+To ensure accurate domain parsing, you should periodically update the multi-part TLD list. The best sources for this information are:
+
+1. **Public Suffix List (PSL)**: The most comprehensive and authoritative source
+   - Website: https://publicsuffix.org/list/
+   - GitHub: https://github.com/publicsuffix/list
+   - This list is maintained by Mozilla and used by browsers and DNS applications
+
+2. **IANA's TLD Database**: The official registry of top-level domains
+   - Website: https://www.iana.org/domains/root/db
+
+3. **Commercial Domain Registrars**: Often provide lists of available TLDs
+   - Examples: GoDaddy, Namecheap, etc.
+
+For the most accurate and comprehensive implementation, consider implementing a parser for the Public Suffix List or using a library that maintains this list (e.g., `publicsuffix2` for Python).
+
 ## API Endpoints
 
 - `/api/uploads` - Get all uploads
-- `/api/slds` - Get all SLDs (Second Level Domains)
-- `/api/slds/{sld}` - Get domains by SLD
+- `/api/domains` - Get all domains
+- `/api/base-domains` - Get only unique base domains (e.g., example.com, example.co.uk) with simplified response format
+- `/api/domains/{domain}` - Get domains by name
 - `/api/dns` - Get all DNS records 
 - `/api/dns/types` - Get unique values for filters
 
@@ -100,8 +128,27 @@ You can filter the API results using the following query parameters:
 - `upload_id` - Filter by specific upload
 - `record_type` - Filter by DNS record type
 - `record_class` - Filter by DNS record class
-- `tld` - Filter by Top Level Domain
-- `sld` - Filter by Second Level Domain
 - `domain` - Search by domain name
+- `base_domains_only` - Only show base domains (e.g., example.com not mail.example.com)
+- `deduplicate` - For DNS records, control whether to show all records or deduplicate
 
-Example: `/api/dns?record_type=A&tld=com&upload_id=upload_20250408120000`
+Examples:
+- `/api/domains?base_domains_only=true` - Show only base domains
+- `/api/base-domains` - Get a simplified list of unique base domains
+- `/api/dns?record_type=A&domain=example.com&deduplicate=false` - Show all A records for example.com without deduplication
+
+### Response Format Examples
+
+1. Base Domains Endpoint (`/api/base-domains`):
+```json
+[
+  {
+    "domain": "example.com",
+    "timestamp": "2025-04-08T12:00:00"
+  },
+  {
+    "domain": "example.co.uk",
+    "timestamp": "2025-04-08T12:00:00"
+  }
+]
+```
diff --git a/main.py b/main.py
index cf5991f..0d2cc7a 100644
--- a/main.py
+++ b/main.py
@@ -139,23 +139,42 @@ async def process_csv_upload(file_content, upload_id, description=None):
         print(traceback.format_exc())
         return 0, 0
 
-# Load domains from database - deduplicated by full domain name
-def load_domains(specific_upload_id: str = None) -> List[Dict]:
+# Load domains from database - deduplicated by full domain name, with optional base domain filtering
+def load_domains(specific_upload_id: str = None, base_domains_only: bool = False) -> List[Dict]:
     try:
         domains = domains_table.all()
         
         # If a specific upload ID is provided, only show domains from that upload
         if specific_upload_id:
             domains = [d for d in domains if d.get('upload_id') == specific_upload_id]
-            return domains
+            if not base_domains_only:
+                return domains
+        
+        # Add the base_domain field to each domain
+        for domain in domains:
+            domain['base_domain'] = extract_base_domain(domain.get('full_domain', ''))
         
         # Sort by timestamp in descending order (newest first)
         domains.sort(key=lambda x: x.get('timestamp', ''), reverse=True)
         
-        # Create a dictionary to track unique domains by full domain name
+        # Create a dictionary to track unique domains
         unique_domains = {}
+        base_domains_set = set()
+        
+        # First pass: collect all base domains
+        if base_domains_only:
+            for domain in domains:
+                base_domains_set.add(domain.get('base_domain', ''))
         
         for domain in domains:
+            # If base_domains_only is True, only keep domains that are base domains themselves
+            if base_domains_only:
+                full_domain = domain.get('full_domain', '')
+                base_domain = domain.get('base_domain', '')
+                
+                if full_domain != base_domain:
+                    continue
+            
             # Create a unique key based on the full domain name
             unique_key = domain.get('full_domain', '')
             
@@ -206,6 +225,90 @@ def load_dns_entries(specific_upload_id: str = None, deduplicate: bool = False)
         print(f"Error loading DNS records from database: {e}")
         return []
 
+# List of known multi-part TLDs
+MULTI_PART_TLDS = [
+    'co.uk', 'org.uk', 'me.uk', 'ac.uk', 'gov.uk', 'net.uk', 'sch.uk',
+    'com.au', 'net.au', 'org.au', 'edu.au', 'gov.au', 'asn.au', 'id.au',
+    'co.nz', 'net.nz', 'org.nz', 'govt.nz', 'ac.nz', 'school.nz', 'geek.nz',
+    'com.sg', 'edu.sg', 'gov.sg', 'net.sg', 'org.sg', 'per.sg',
+    'co.za', 'org.za', 'web.za', 'net.za', 'gov.za', 'ac.za',
+    'com.br', 'net.br', 'org.br', 'gov.br', 'edu.br',
+    'co.jp', 'ac.jp', 'go.jp', 'or.jp', 'ne.jp', 'gr.jp',
+    'co.in', 'firm.in', 'net.in', 'org.in', 'gen.in', 'ind.in',
+    'edu.cn', 'gov.cn', 'net.cn', 'org.cn', 'com.cn', 'ac.cn',
+    'com.mx', 'net.mx', 'org.mx', 'edu.mx', 'gob.mx'
+]
+
+# Extract the base domain (SLD+TLD) from a full domain name
+def extract_base_domain(domain: str) -> str:
+    if not domain:
+        return domain
+        
+    # Remove trailing dot if present
+    if domain.endswith('.'):
+        domain = domain[:-1]
+        
+    parts = domain.split('.')
+    
+    # Check if the domain has enough parts
+    if len(parts) <= 1:
+        return domain
+        
+    # Check for known multi-part TLDs first
+    for tld in MULTI_PART_TLDS:
+        tld_parts = tld.split('.')
+        if len(parts) > len(tld_parts) and '.'.join(parts[-len(tld_parts):]) == tld:
+            # The domain has a multi-part TLD, extract SLD + multi-part TLD
+            return parts[-len(tld_parts)-1] + '.' + tld
+    
+    # Default case: extract last two parts
+    if len(parts) > 1:
+        return '.'.join(parts[-2:])
+        
+    return domain
+
+# Get all unique base domains from the database
+def get_unique_base_domains(specific_upload_id: str = None) -> List[Dict]:
+    try:
+        domains = domains_table.all()
+        
+        # If a specific upload ID is provided, only show domains from that upload
+        if specific_upload_id:
+            domains = [d for d in domains if d.get('upload_id') == specific_upload_id]
+        
+        # Add the base_domain field to each domain
+        for domain in domains:
+            domain['base_domain'] = extract_base_domain(domain.get('full_domain', ''))
+        
+        # Sort by timestamp in descending order (newest first)
+        domains.sort(key=lambda x: x.get('timestamp', ''), reverse=True)
+        
+        # Create dictionaries to track unique base domains
+        unique_base_domains = {}
+        
+        # Process each domain and keep only unique base domains
+        for domain in domains:
+            base_domain = domain.get('base_domain', '')
+            
+            # Skip if no base domain
+            if not base_domain:
+                continue
+                
+            # Check if this base domain has been seen before
+            if base_domain not in unique_base_domains:
+                # Create a new entry for this base domain - with simplified fields
+                base_domain_entry = {
+                    'domain': base_domain,
+                    'timestamp': domain.get('timestamp')
+                }
+                unique_base_domains[base_domain] = base_domain_entry
+        
+        # Return the list of unique base domains
+        return list(unique_base_domains.values())
+    except Exception as e:
+        print(f"Error getting unique base domains: {e}")
+        return []
+
 # Get unique values for filter dropdowns
 def get_unique_values(entries: List[Dict]) -> Dict[str, Set]:
     unique_values = {
@@ -249,16 +352,21 @@ def delete_upload(upload_id):
 
 # Routes
 @app.get("/", response_class=HTMLResponse)
-async def home(request: Request, upload_id: Optional[str] = None):
-    """Home page with upload form and SLD listing"""
-    domains = load_domains(upload_id)
+async def home(
+    request: Request, 
+    upload_id: Optional[str] = None,
+    base_domains_only: Optional[bool] = False
+):
+    """Home page with upload form and domain listing"""
+    domains = load_domains(upload_id, base_domains_only)
     uploads = get_uploads()
     return templates.TemplateResponse(
         "index.html", 
         {
             "request": request, 
             "domains": domains,
-            "uploads": uploads
+            "uploads": uploads,
+            "base_domains_only": base_domains_only
         }
     )
 
@@ -370,12 +478,22 @@ async def get_all_uploads():
     return get_uploads()
 
 @app.get("/api/domains", response_model=List[Dict])
-async def get_domains(upload_id: Optional[str] = None):
-    """API endpoint that returns all domains with optional filter by upload_id"""
-    # The load_domains function now handles deduplication and upload_id filtering
-    domains = load_domains(upload_id)
+async def get_domains(
+    upload_id: Optional[str] = None,
+    base_domains_only: Optional[bool] = False
+):
+    """API endpoint that returns all domains with optional filtering"""
+    # The load_domains function handles deduplication and filtering
+    domains = load_domains(upload_id, base_domains_only)
     return domains
 
+@app.get("/api/base-domains", response_model=List[Dict])
+async def get_base_domains(upload_id: Optional[str] = None):
+    """API endpoint that returns only unique base domains"""
+    # Get only the unique base domains
+    base_domains = get_unique_base_domains(upload_id)
+    return base_domains
+
 @app.get("/api/domains/{domain}", response_model=List[Dict])
 async def get_domains_by_name(domain: str, upload_id: Optional[str] = None):
     """API endpoint that returns domains matching a specific domain name with optional filter by upload_id"""
diff --git a/templates/index.html b/templates/index.html
index 91846fb..7d0bef1 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -61,6 +61,23 @@
             font-size: 0.9em;
             color: #0f5132;
         }
+        .base-domain-badge {
+            display: inline-block;
+            padding: 3px 7px;
+            background-color: #cfe2ff;
+            border-radius: 4px;
+            font-size: 0.9em;
+            color: #0a58ca;
+        }
+        .same-domain-badge {
+            display: inline-block;
+            padding: 3px 7px;
+            background-color: #e9ecef;
+            border-radius: 4px;
+            font-size: 0.9em;
+            color: #6c757d;
+            font-style: italic;
+        }
         .api-section {
             margin-top: 30px;
             padding: 15px;
@@ -127,12 +144,48 @@
         }
         .filter-form {
             margin-bottom: 20px;
+            background-color: #f9f9f9;
+            padding: 15px;
+            border-radius: 5px;
+        }
+        .filter-row {
+            display: flex;
+            flex-wrap: wrap;
+            gap: 15px;
+            align-items: flex-end;
+        }
+        .filter-group {
+            display: flex;
+            flex-direction: column;
+        }
+        .filter-group label {
+            font-weight: bold;
+            margin-bottom: 5px;
+            font-size: 0.9em;
         }
         .filter-select {
             padding: 8px 12px;
             border: 1px solid #ddd;
             border-radius: 4px;
-            margin-right: 10px;
+            min-width: 150px;
+        }
+        .btn-sm {
+            padding: 8px 16px;
+            font-size: 0.9em;
+        }
+        .reset-button {
+            display: inline-block;
+            padding: 8px 16px;
+            background-color: #f44336;
+            color: white;
+            text-decoration: none;
+            border-radius: 4px;
+            font-weight: bold;
+            font-size: 0.9em;
+        }
+        .reset-button:hover {
+            background-color: #e53935;
+            color: white;
         }
     </style>
 </head>
@@ -199,15 +252,32 @@
         <div class="filter-form">
             <h2>Domain List</h2>
             <form id="filterForm" method="get">
-                <label for="upload_filter">Filter by upload:</label>
-                <select id="upload_filter" name="upload_id" class="filter-select" onchange="this.form.submit()">
-                    <option value="">All uploads</option>
-                    {% for upload in uploads %}
-                    <option value="{{ upload.id }}" {% if request.query_params.get('upload_id') == upload.id %}selected{% endif %}>
-                        {{ upload.filename }} - {{ upload.timestamp.replace('T', ' ').split('.')[0] }}
-                    </option>
-                    {% endfor %}
-                </select>
+                <div class="filter-row">
+                    <div class="filter-group">
+                        <label for="upload_filter">Filter by upload:</label>
+                        <select id="upload_filter" name="upload_id" class="filter-select">
+                            <option value="">All uploads</option>
+                            {% for upload in uploads %}
+                            <option value="{{ upload.id }}" {% if request.query_params.get('upload_id') == upload.id %}selected{% endif %}>
+                                {{ upload.filename }} - {{ upload.timestamp.replace('T', ' ').split('.')[0] }}
+                            </option>
+                            {% endfor %}
+                        </select>
+                    </div>
+                    
+                    <div class="filter-group">
+                        <label for="base_domains_only">Show base domains only:</label>
+                        <select id="base_domains_only" name="base_domains_only" class="filter-select">
+                            <option value="false" {% if request.query_params.get('base_domains_only', 'false') == 'false' %}selected{% endif %}>No (Show All)</option>
+                            <option value="true" {% if request.query_params.get('base_domains_only') == 'true' %}selected{% endif %}>Yes (example.com only)</option>
+                        </select>
+                    </div>
+                    
+                    <div class="filter-buttons">
+                        <button type="submit" class="btn btn-sm">Apply Filters</button>
+                        <a href="/" class="reset-button">Reset</a>
+                    </div>
+                </div>
             </form>
         </div>
         
@@ -215,8 +285,10 @@
             <h3>API Endpoints</h3>
             <p>Get all uploads: <code>/api/uploads</code></p>
             <p>Get all domains: <code>/api/domains</code></p>
+            <p>Get only base domains: <code>/api/base-domains</code> (simplified format: <code>{"domain": "example.com", "timestamp": "..."}</code>)</p>
             <p>Get domains by name: <code>/api/domains/{domain}</code></p>
             <p>Filter by upload: <code>/api/domains?upload_id={upload_id}</code></p>
+            <p>Show base domains only: <code>/api/domains?base_domains_only=true</code></p>
         </div>
         
         {% if domains %}
@@ -225,6 +297,9 @@
                 <thead>
                     <tr>
                         <th>Domain</th>
+                        {% if not base_domains_only %}
+                        <th>Base Domain</th>
+                        {% endif %}
                         <th>Upload Date</th>
                     </tr>
                 </thead>
@@ -232,6 +307,9 @@
                     {% for item in domains %}
                     <tr>
                         <td><span class="domain-badge">{{ item.full_domain }}</span></td>
+                        {% if not base_domains_only %}
+                        <td>{% if item.base_domain != item.full_domain %}<span class="base-domain-badge">{{ item.base_domain }}</span>{% else %}<span class="same-domain-badge">Same as domain</span>{% endif %}</td>
+                        {% endif %}
                         <td>{{ item.timestamp.replace('T', ' ').split('.')[0] if item.get('timestamp') else 'N/A' }}</td>
                     </tr>
                     {% endfor %}