diff --git a/jupyter_ydoc/__init__.py b/jupyter_ydoc/__init__.py
index 8bca86c..5d9e55e 100644
--- a/jupyter_ydoc/__init__.py
+++ b/jupyter_ydoc/__init__.py
@@ -3,11 +3,11 @@
 
 import sys
 
-from ._version import __version__  # noqa
-from .yblob import YBlob  # noqa
-from .yfile import YFile  # noqa
-from .ynotebook import YNotebook  # noqa
-from .yunicode import YUnicode  # noqa
+from ._version import __version__
+from .yblob import YBlob
+from .yfile import YFile
+from .ynotebook import YNotebook
+from .yunicode import YUnicode
 
 # See compatibility note on `group` keyword in
 # https://docs.python.org/3/library/importlib.metadata.html#entry-points
diff --git a/jupyter_ydoc/ybasedoc.py b/jupyter_ydoc/ybasedoc.py
index 44f9799..3d9aa81 100644
--- a/jupyter_ydoc/ybasedoc.py
+++ b/jupyter_ydoc/ybasedoc.py
@@ -2,9 +2,9 @@
 # Distributed under the terms of the Modified BSD License.
 
 from abc import ABC, abstractmethod
-from typing import Any, Callable, Optional
+from typing import Any, Callable, Dict, Optional
 
-import y_py as Y
+from pycrdt import Doc, Map
 
 
 class YBaseDoc(ABC):
@@ -15,19 +15,20 @@ class YBaseDoc(ABC):
     subscribe to changes in the document.
     """
 
-    def __init__(self, ydoc: Optional[Y.YDoc] = None):
+    def __init__(self, ydoc: Optional[Doc] = None):
         """
         Constructs a YBaseDoc.
 
-        :param ydoc: The :class:`y_py.YDoc` that will hold the data of the document, if provided.
-        :type ydoc: :class:`y_py.YDoc`, optional.
+        :param ydoc: The :class:`pycrdt.Doc` that will hold the data of the document, if provided.
+        :type ydoc: :class:`pycrdt.Doc`, optional.
         """
         if ydoc is None:
-            self._ydoc = Y.YDoc()
+            self._ydoc = Doc()
         else:
             self._ydoc = ydoc
-        self._ystate = self._ydoc.get_map("state")
-        self._subscriptions = {}
+        self._ystate = Map()
+        self._ydoc["state"] = self._ystate
+        self._subscriptions: Dict[Any, str] = {}
 
     @property
     @abstractmethod
@@ -40,22 +41,22 @@ def version(self) -> str:
         """
 
     @property
-    def ystate(self) -> Y.YMap:
+    def ystate(self) -> Map:
         """
-        A :class:`y_py.YMap` containing the state of the document.
+        A :class:`pycrdt.Map` containing the state of the document.
 
         :return: The document's state.
-        :rtype: :class:`y_py.YMap`
+        :rtype: :class:`pycrdt.Map`
         """
         return self._ystate
 
     @property
-    def ydoc(self) -> Y.YDoc:
+    def ydoc(self) -> Doc:
         """
-        The underlying :class:`y_py.YDoc` that contains the data.
+        The underlying :class:`pycrdt.Doc` that contains the data.
 
         :return: The document's ydoc.
-        :rtype: :class:`y_py.YDoc`
+        :rtype: :class:`pycrdt.Doc`
         """
         return self._ydoc
 
@@ -87,7 +88,7 @@ def dirty(self) -> Optional[bool]:
         :return: Whether the document is dirty.
         :rtype: Optional[bool]
         """
-        return self._ystate["dirty"]
+        return self._ystate.get("dirty")
 
     @dirty.setter
     def dirty(self, value: bool) -> None:
@@ -97,8 +98,7 @@ def dirty(self, value: bool) -> None:
         :param value: Whether the document is clean or dirty.
         :type value: bool
         """
-        with self._ydoc.begin_transaction() as t:
-            self._ystate.set(t, "dirty", value)
+        self._ystate["dirty"] = value
 
     @property
     def path(self) -> Optional[str]:
@@ -118,8 +118,7 @@ def path(self, value: str) -> None:
         :param value: Document's path.
         :type value: str
         """
-        with self._ydoc.begin_transaction() as t:
-            self._ystate.set(t, "path", value)
+        self._ystate["path"] = value
 
     @abstractmethod
     def get(self) -> Any:
diff --git a/jupyter_ydoc/yblob.py b/jupyter_ydoc/yblob.py
index 3950361..9cfdcc0 100644
--- a/jupyter_ydoc/yblob.py
+++ b/jupyter_ydoc/yblob.py
@@ -5,7 +5,7 @@
 from functools import partial
 from typing import Any, Callable, Optional, Union
 
-import y_py as Y
+from pycrdt import Doc, Map
 
 from .ybasedoc import YBaseDoc
 
@@ -28,15 +28,16 @@ class YBlob(YBaseDoc):
         }
     """
 
-    def __init__(self, ydoc: Optional[Y.YDoc] = None):
+    def __init__(self, ydoc: Optional[Doc] = None):
         """
         Constructs a YBlob.
 
-        :param ydoc: The :class:`y_py.YDoc` that will hold the data of the document, if provided.
-        :type ydoc: :class:`y_py.YDoc`, optional.
+        :param ydoc: The :class:`pycrdt.Doc` that will hold the data of the document, if provided.
+        :type ydoc: :class:`pycrdt.Doc`, optional.
         """
         super().__init__(ydoc)
-        self._ysource = self._ydoc.get_map("source")
+        self._ysource = Map()
+        self._ydoc["source"] = self._ysource
 
     @property
     def version(self) -> str:
@@ -55,7 +56,7 @@ def get(self) -> bytes:
         :return: Document's content.
         :rtype: bytes
         """
-        return base64.b64decode(self._ysource.get("base64", "").encode())
+        return base64.b64decode(self._ysource["base64"].encode())
 
     def set(self, value: Union[bytes, str]) -> None:
         """
@@ -66,8 +67,7 @@ def set(self, value: Union[bytes, str]) -> None:
         """
         if isinstance(value, bytes):
             value = base64.b64encode(value).decode()
-        with self._ydoc.begin_transaction() as t:
-            self._ysource.set(t, "base64", value)
+        self._ysource["base64"] = value
 
     def observe(self, callback: Callable[[str, Any], None]) -> None:
         """
diff --git a/jupyter_ydoc/ynotebook.py b/jupyter_ydoc/ynotebook.py
index 47ae466..ea134ed 100644
--- a/jupyter_ydoc/ynotebook.py
+++ b/jupyter_ydoc/ynotebook.py
@@ -7,7 +7,7 @@
 from typing import Any, Callable, Dict, Optional
 from uuid import uuid4
 
-import y_py as Y
+from pycrdt import Array, Doc, Map, Text
 
 from .utils import cast_all
 from .ybasedoc import YBaseDoc
@@ -47,16 +47,18 @@ class YNotebook(YBaseDoc):
         }
     """
 
-    def __init__(self, ydoc: Optional[Y.YDoc] = None):
+    def __init__(self, ydoc: Optional[Doc] = None):
         """
         Constructs a YNotebook.
 
-        :param ydoc: The :class:`y_py.YDoc` that will hold the data of the document, if provided.
-        :type ydoc: :class:`y_py.YDoc`, optional.
+        :param ydoc: The :class:`pycrdt.Doc` that will hold the data of the document, if provided.
+        :type ydoc: :class:`pycrdt.Doc`, optional.
         """
         super().__init__(ydoc)
-        self._ymeta = self._ydoc.get_map("meta")
-        self._ycells = self._ydoc.get_array("cells")
+        self._ymeta = Map()
+        self._ycells = Array()
+        self._ydoc["meta"] = self._ymeta
+        self._ydoc["cells"] = self._ycells
 
     @property
     def version(self) -> str:
@@ -74,7 +76,7 @@ def ycells(self):
         Returns the Y-cells.
 
         :return: The Y-cells.
-        :rtype: :class:`y_py.YArray`
+        :rtype: :class:`pycrdt.Array`
         """
         return self._ycells
 
@@ -98,8 +100,8 @@ def get_cell(self, index: int) -> Dict[str, Any]:
         :return: A cell.
         :rtype: Dict[str, Any]
         """
-        meta = json.loads(self._ymeta.to_json())
-        cell = json.loads(self._ycells[index].to_json())
+        meta = json.loads(str(self._ymeta))
+        cell = json.loads(str(self._ycells[index]))
         cast_all(cell, float, int)  # cells coming from Yjs have e.g. execution_count as float
         if "id" in cell and meta["nbformat"] == 4 and meta["nbformat_minor"] <= 4:
             # strip cell IDs if we have notebook format 4.0-4.4
@@ -112,25 +114,18 @@ def get_cell(self, index: int) -> Dict[str, Any]:
             del cell["attachments"]
         return cell
 
-    def append_cell(self, value: Dict[str, Any], txn: Optional[Y.YTransaction] = None) -> None:
+    def append_cell(self, value: Dict[str, Any]) -> None:
         """
         Appends a cell.
 
         :param value: A cell.
         :type value: Dict[str, Any]
-
-        :param txn: A YTransaction, defaults to None
-        :type txn: :class:`y_py.YTransaction`, optional.
         """
         ycell = self.create_ycell(value)
-        if txn is None:
-            with self._ydoc.begin_transaction() as txn:
-                self._ycells.append(txn, ycell)
-        else:
-            self._ycells.append(txn, ycell)
+        self._ycells.append(ycell)
 
     def set_cell(
-        self, index: int, value: Dict[str, Any], txn: Optional[Y.YTransaction] = None
+        self, index: int, value: Dict[str, Any]
     ) -> None:
         """
         Sets a cell into indicated position.
@@ -140,14 +135,11 @@ def set_cell(
 
         :param value: A cell.
         :type value: Dict[str, Any]
-
-        :param txn: A YTransaction, defaults to None
-        :type txn: :class:`y_py.YTransaction`, optional.
         """
         ycell = self.create_ycell(value)
-        self.set_ycell(index, ycell, txn)
+        self.set_ycell(index, ycell)
 
-    def create_ycell(self, value: Dict[str, Any]) -> Y.YMap:
+    def create_ycell(self, value: Dict[str, Any]) -> Map:
         """
         Creates YMap with the content of the cell.
 
@@ -155,7 +147,7 @@ def create_ycell(self, value: Dict[str, Any]) -> Y.YMap:
         :type value: Dict[str, Any]
 
         :return: A new cell.
-        :rtype: :class:`y_py.YMap`
+        :rtype: :class:`pycrdt.Map`
         """
         cell = copy.deepcopy(value)
         if "id" not in cell:
@@ -163,18 +155,18 @@ def create_ycell(self, value: Dict[str, Any]) -> Y.YMap:
         cell_type = cell["cell_type"]
         cell_source = cell["source"]
         cell_source = "".join(cell_source) if isinstance(cell_source, list) else cell_source
-        cell["source"] = Y.YText(cell_source)
-        cell["metadata"] = Y.YMap(cell.get("metadata", {}))
+        cell["source"] = Text(cell_source)
+        cell["metadata"] = Map(cell.get("metadata", {}))
 
         if cell_type in ("raw", "markdown"):
             if "attachments" in cell and not cell["attachments"]:
                 del cell["attachments"]
         elif cell_type == "code":
-            cell["outputs"] = Y.YArray(cell.get("outputs", []))
+            cell["outputs"] = Array(cell.get("outputs", []))
 
-        return Y.YMap(cell)
+        return Map(cell)
 
-    def set_ycell(self, index: int, ycell: Y.YMap, txn: Optional[Y.YTransaction] = None) -> None:
+    def set_ycell(self, index: int, ycell: Map) -> None:
         """
         Sets a Y cell into the indicated position.
 
@@ -182,18 +174,9 @@ def set_ycell(self, index: int, ycell: Y.YMap, txn: Optional[Y.YTransaction] = N
         :type index: int
 
         :param ycell: A YMap with the content of a cell.
-        :type ycell: :class:`y_py.YMap`
-
-        :param txn: A YTransaction, defaults to None
-        :type txn: :class:`y_py.YTransaction`, optional.
+        :type ycell: :class:`pycrdt.Map`
         """
-        if txn is None:
-            with self._ydoc.begin_transaction() as txn:
-                self._ycells.delete(txn, index)
-                self._ycells.insert(txn, index, ycell)
-        else:
-            self._ycells.delete(txn, index)
-            self._ycells.insert(txn, index, ycell)
+        self._ycells[index] = ycell
 
     def get(self) -> Dict:
         """
@@ -202,7 +185,7 @@ def get(self) -> Dict:
         :return: Document's content.
         :rtype: Dict
         """
-        meta = json.loads(self._ymeta.to_json())
+        meta = json.loads(str(self._ymeta))
         cast_all(meta, float, int)  # notebook coming from Yjs has e.g. nbformat as float
         cells = []
         for i in range(len(self._ycells)):
@@ -247,29 +230,23 @@ def set(self, value: Dict) -> None:
             }
         ]
 
-        with self._ydoc.begin_transaction() as t:
+        with self._ydoc.transaction():
             # clear document
-            cells_len = len(self._ycells)
-            for key in self._ymeta:
-                self._ymeta.pop(t, key)
-            if cells_len:
-                self._ycells.delete_range(t, 0, cells_len)
-            for key in [k for k in self._ystate if k not in ("dirty", "path")]:
-                self._ystate.pop(t, key)
+            self._ymeta.clear()
+            self._ycells.clear()
+            for key in [k for k in self._ystate.keys() if k not in ("dirty", "path")]:
+                del self._ystate[key]
 
             # initialize document
-            # workaround for https://github.com/y-crdt/ypy/issues/126:
-            # self._ycells.extend(t, [self.create_ycell(cell) for cell in cells])
-            for cell in cells:
-                self._ycells.append(t, self.create_ycell(cell))
-            self._ymeta.set(t, "nbformat", nb.get("nbformat", NBFORMAT_MAJOR_VERSION))
-            self._ymeta.set(t, "nbformat_minor", nb.get("nbformat_minor", NBFORMAT_MINOR_VERSION))
+            self._ycells.extend([self.create_ycell(cell) for cell in cells])
+            self._ymeta["nbformat"] = nb.get("nbformat", NBFORMAT_MAJOR_VERSION)
+            self._ymeta["nbformat_minor"] = nb.get("nbformat_minor", NBFORMAT_MINOR_VERSION)
 
             metadata = nb.get("metadata", {})
             metadata.setdefault("language_info", {"name": ""})
             metadata.setdefault("kernelspec", {"name": "", "display_name": ""})
 
-            self._ymeta.set(t, "metadata", Y.YMap(metadata))
+            self._ymeta["metadata"] = Map(metadata)
 
     def observe(self, callback: Callable[[str, Any], None]) -> None:
         """
diff --git a/jupyter_ydoc/yunicode.py b/jupyter_ydoc/yunicode.py
index 9e416bb..0dda6ea 100644
--- a/jupyter_ydoc/yunicode.py
+++ b/jupyter_ydoc/yunicode.py
@@ -4,7 +4,7 @@
 from functools import partial
 from typing import Any, Callable, Optional
 
-import y_py as Y
+from pycrdt import Doc, Text
 
 from .ybasedoc import YBaseDoc
 
@@ -23,15 +23,16 @@ class YUnicode(YBaseDoc):
         }
     """
 
-    def __init__(self, ydoc: Optional[Y.YDoc] = None):
+    def __init__(self, ydoc: Optional[Doc] = None):
         """
         Constructs a YUnicode.
 
-        :param ydoc: The :class:`y_py.YDoc` that will hold the data of the document, if provided.
-        :type ydoc: :class:`y_py.YDoc`, optional.
+        :param ydoc: The :class:`pycrdt.Doc` that will hold the data of the document, if provided.
+        :type ydoc: :class:`pycrdt.Doc`, optional.
         """
         super().__init__(ydoc)
-        self._ysource = self._ydoc.get_text("source")
+        self._ysource = Text()
+        self._ydoc["source"] = self._ysource
 
     @property
     def version(self) -> str:
@@ -59,14 +60,12 @@ def set(self, value: str) -> None:
         :param value: The content of the document.
         :type value: str
         """
-        with self._ydoc.begin_transaction() as t:
+        with self._ydoc.transaction():
             # clear document
-            source_len = len(self._ysource)
-            if source_len:
-                self._ysource.delete_range(t, 0, source_len)
+            del self._ysource[:]
             # initialize document
             if value:
-                self._ysource.extend(t, value)
+                self._ysource += value
 
     def observe(self, callback: Callable[[str, Any], None]) -> None:
         """
diff --git a/pyproject.toml b/pyproject.toml
index 7923d5c..4aee802 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,8 +12,8 @@ description = "Document structures for collaborative editing using Ypy"
 requires-python = ">=3.7"
 keywords = ["jupyter", "ypy"]
 dependencies = [
-    "importlib_metadata >=3.6; python_version<\"3.10\"",
-    "y-py >=0.6.0,<0.7.0",
+    "importlib_metadata >=3.6; python_version<'3.10'",
+    "pycrdt >=0.3.1,<0.4.0",
 ]
 
 [[project.authors]]
diff --git a/tests/test_ypy_yjs.py b/tests/test_ypy_yjs.py
index 5ba157b..ea1804f 100644
--- a/tests/test_ypy_yjs.py
+++ b/tests/test_ypy_yjs.py
@@ -6,7 +6,7 @@
 from pathlib import Path
 
 import pytest
-import y_py as Y
+from pycrdt import Doc
 from websockets import connect  # type: ignore
 from ypy_websocket import WebsocketProvider
 
@@ -27,7 +27,7 @@ def stringify_source(nb: dict) -> dict:
 
 
 class YTest:
-    def __init__(self, ydoc: Y.YDoc, timeout: float = 1.0):
+    def __init__(self, ydoc: Doc, timeout: float = 1.0):
         self.timeout = timeout
         self.ytest = ydoc.get_map("_test")
         with ydoc.begin_transaction() as t:
@@ -51,7 +51,7 @@ def source(self):
 @pytest.mark.asyncio
 @pytest.mark.parametrize("yjs_client", "0", indirect=True)
 async def test_ypy_yjs_0(yws_server, yjs_client):
-    ydoc = Y.YDoc()
+    ydoc = Doc()
     ynotebook = YNotebook(ydoc)
     websocket = await connect("ws://localhost:1234/my-roomname")
     WebsocketProvider(ydoc, websocket)
@@ -64,7 +64,7 @@ async def test_ypy_yjs_0(yws_server, yjs_client):
 
 def test_plotly_renderer():
     """This test checks in particular that the type cast is not breaking the data."""
-    ydoc = Y.YDoc()
+    ydoc = Doc()
     ynotebook = YNotebook(ydoc)
     nb = stringify_source(json.loads((files_dir / "plotly_renderer.ipynb").read_text()))
     ynotebook.source = nb