diff --git a/ludic/attrs.py b/ludic/attrs.py
index 6f17884..422a67f 100644
--- a/ludic/attrs.py
+++ b/ludic/attrs.py
@@ -119,6 +119,13 @@ class HtmxAttrs(Attrs, total=False):
     hx_ws: Annotated[str, Alias("hx-ws")]
     hx_sse: Annotated[str, Alias("hx-sse")]
 
+    # Extensions
+    ws_connect: Annotated[str, Alias("ws-connect")]
+    ws_send: Annotated[str, Alias("ws-send")]
+    sse_connect: Annotated[str, Alias("sse-connect")]
+    sse_send: Annotated[str, Alias("sse-send")]
+    sse_swap: Annotated[str, Alias("sse-swap")]
+
 
 class WindowEventAttrs(Attrs, total=False):
     """Event Attributes for HTML elements."""
diff --git a/ludic/format.py b/ludic/format.py
index 725192c..8574f48 100644
--- a/ludic/format.py
+++ b/ludic/format.py
@@ -1,16 +1,34 @@
 import html
+import inspect
 import random
 import re
 from collections.abc import Mapping
 from contextvars import ContextVar
-from typing import Any, Final, TypeVar
+from functools import lru_cache
+from typing import Any, Final, TypeVar, get_type_hints
 
 T = TypeVar("T")
 
 _EXTRACT_NUMBER_RE: Final[re.Pattern[str]] = re.compile(r"\{(\d+:id)\}")
-_ALIASES: Final[dict[str, str]] = {
-    "classes": "class",
-}
+
+
+@lru_cache
+def _load_attrs_aliases() -> Mapping[str, str]:
+    from ludic import attrs
+
+    result = {}
+    for name, cls in inspect.getmembers(attrs, inspect.isclass):
+        if not name.endswith("Attrs"):
+            continue
+
+        hints = get_type_hints(cls, include_extras=True)
+        for key, value in hints.items():
+            if metadata := getattr(value, "__metadata__", None):
+                for meta in metadata:
+                    if isinstance(meta, attrs.Alias):
+                        result[key] = str(meta)
+
+    return result
 
 
 def format_attr_value(key: str, value: Any, is_html: bool = False) -> str:
@@ -67,13 +85,13 @@ def format_attrs(attrs: Mapping[str, Any], is_html: bool = False) -> dict[str, A
     Returns:
         dict[str, Any]: The formatted attributes.
     """
+    aliases = _load_attrs_aliases()
     result: dict[str, str] = {}
+
     for key, value in attrs.items():
         if formatted_value := format_attr_value(key, value, is_html=is_html):
-            if key in _ALIASES:
-                alias = _ALIASES[key]
-            elif key.startswith("on_"):
-                alias = key.replace("on_", "on")
+            if key in aliases:
+                alias = aliases[key]
             else:
                 alias = key.strip("_").replace("_", "-")
 
diff --git a/tests/test_elements.py b/tests/test_elements.py
index 075d95a..01872fd 100644
--- a/tests/test_elements.py
+++ b/tests/test_elements.py
@@ -161,6 +161,17 @@ def test_data_attributes() -> None:
     assert dom.to_html() == '<div data-foo="1" data-bar="test">content</div>'
 
 
+def test_htmx_attributes() -> None:
+    assert html.button(
+        "Get Info!",
+        hx_get="/info", hx_on__before_request="alert('Making a request!')",
+    ).to_html() == (  # type: ignore
+        '<button hx-get="/info" hx-on--before-request="alert(\'Making a request!\')">'
+            "Get Info!"
+        "</button>"
+    )  # fmt: skip
+
+
 def test_all_elements() -> None:
     assert html.div("test", id="div").to_html() == '<div id="div">test</div>'
     assert html.span("test", id="span").to_html() == '<span id="span">test</span>'
diff --git a/tests/test_formatting.py b/tests/test_formatting.py
index f9ea0d5..e4b986b 100644
--- a/tests/test_formatting.py
+++ b/tests/test_formatting.py
@@ -104,3 +104,16 @@ def test_attributes() -> None:
     assert format_attrs({"class_": "a b c", "classes": ["more", "classes"]}) == {
         "class": "a b c more classes"
     }
+
+    assert format_attrs(
+        {
+            "hx_on_htmx_before_request": "alert('test')",
+            "hx_on__after_request": "alert('test2')",
+        }
+    ) == {
+        "hx-on-htmx-before-request": "alert('test')",
+        "hx-on--after-request": "alert('test2')",
+    }
+    assert format_attrs(
+        {"hx-on:htmx:before-request": "alert('Making a request!')"}
+    ) == {"hx-on:htmx:before-request": "alert('Making a request!')"}