diff --git a/crawl4ai/deep_crawling/filters.py b/crawl4ai/deep_crawling/filters.py
index 122be482..8d0bcc4d 100644
--- a/crawl4ai/deep_crawling/filters.py
+++ b/crawl4ai/deep_crawling/filters.py
@@ -337,6 +337,15 @@ class ContentTypeFilter(URLFilter):
         "sqlite": "application/vnd.sqlite3",
         # Placeholder
         "unknown": "application/octet-stream",  # Fallback for unknown file types
+        # php
+        "php": "application/x-httpd-php",
+        "php3": "application/x-httpd-php",
+        "php4": "application/x-httpd-php",
+        "php5": "application/x-httpd-php",
+        "php7": "application/x-httpd-php",
+        "phtml": "application/x-httpd-php",
+        "phps": "application/x-httpd-php-source",
+
     }
 
     @staticmethod
diff --git a/tests/deep_crwaling/test_filter.py b/tests/deep_crwaling/test_filter.py
new file mode 100644
index 00000000..29ada087
--- /dev/null
+++ b/tests/deep_crwaling/test_filter.py
@@ -0,0 +1,75 @@
+# // File: tests/deep_crawling/test_filters.py
+import pytest
+from urllib.parse import urlparse
+from crawl4ai import ContentTypeFilter, URLFilter 
+
+# Minimal URLFilter base class stub if not already importable directly for tests
+# In a real scenario, this would be imported from the library
+if not hasattr(URLFilter, '_update_stats'): # Check if it's a basic stub
+    class URLFilter: # Basic stub for testing if needed
+        def __init__(self, name=None): self.name = name
+        def apply(self, url: str) -> bool: raise NotImplementedError
+        def _update_stats(self, passed: bool): pass # Mock implementation
+
+# Assume ContentTypeFilter is structured as discussed. If its definition is not fully
+# available for direct import in the test environment, a more elaborate stub or direct
+# instantiation of the real class (if possible) would be needed.
+# For this example, we assume ContentTypeFilter can be imported and used.
+
+class TestContentTypeFilter:
+    @pytest.mark.parametrize(
+        "url, allowed_types, expected",
+        [
+            # Existing tests (examples)
+            ("http://example.com/page.html", ["text/html"], True),
+            ("http://example.com/page.json", ["application/json"], True),
+            ("http://example.com/image.png", ["text/html"], False),
+            ("http://example.com/document.pdf", ["application/pdf"], True),
+            ("http://example.com/page", ["text/html"], True), # No extension, allowed
+            ("http://example.com/page", ["text/html"], False), # No extension, disallowed
+            ("http://example.com/page.unknown", ["text/html"], False), # Unknown extension
+            
+            # Tests for PHP extensions
+            ("http://example.com/index.php", ["application/x-httpd-php"], True),
+            ("http://example.com/script.php3", ["application/x-httpd-php"], True),
+            ("http://example.com/legacy.php4", ["application/x-httpd-php"], True),
+            ("http://example.com/main.php5", ["application/x-httpd-php"], True),
+            ("http://example.com/api.php7", ["application/x-httpd-php"], True),
+            ("http://example.com/index.phtml", ["application/x-httpd-php"], True),
+            ("http://example.com/source.phps", ["application/x-httpd-php-source"], True),
+
+            # Test rejection of PHP extensions
+            ("http://example.com/index.php", ["text/html"], False),
+            ("http://example.com/script.php3", ["text/plain"], False),
+            ("http://example.com/source.phps", ["application/x-httpd-php"], False), # Mismatch MIME
+            ("http://example.com/source.php", ["application/x-httpd-php-source"], False), # Mismatch MIME for .php
+
+            # Test case-insensitivity of extensions in URL
+            ("http://example.com/PAGE.HTML", ["text/html"], True),
+            ("http://example.com/INDEX.PHP", ["application/x-httpd-php"], True),
+            ("http://example.com/SOURCE.PHPS", ["application/x-httpd-php-source"], True),
+
+            # Test case-insensitivity of allowed_types
+            ("http://example.com/index.php", ["APPLICATION/X-HTTPD-PHP"], True),
+        ],
+    )
+    def test_apply(self, url, allowed_types, expected):
+        content_filter = ContentTypeFilter(
+            allowed_types=allowed_types
+        )
+        assert content_filter.apply(url) == expected
+
+    @pytest.mark.parametrize(
+        "url, expected_extension",
+        [
+            ("http://example.com/file.html", "html"),
+            ("http://example.com/file.tar.gz", "gz"),
+            ("http://example.com/path/", ""),
+            ("http://example.com/nodot", ""),
+            ("http://example.com/.config", "config"), # hidden file with extension
+            ("http://example.com/path/to/archive.BIG.zip", "zip"), # Case test
+        ]
+    )
+    def test_extract_extension(self, url, expected_extension):
+        # Test the static method directly
+        assert ContentTypeFilter._extract_extension(url) == expected_extension