diff --git a/Tests/images/ani/aero_busy.ani b/Tests/images/ani/aero_busy.ani
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diff --git a/Tests/images/ani/posy_busy.ani b/Tests/images/ani/posy_busy.ani
new file mode 100644
index 000000000..8ac0abef5
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diff --git a/Tests/images/ani/stopwtch.ani b/Tests/images/ani/stopwtch.ani
new file mode 100644
index 000000000..1b3461ef5
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diff --git a/src/PIL/AniImagePlugin.py b/src/PIL/AniImagePlugin.py
new file mode 100644
index 000000000..af3af6368
--- /dev/null
+++ b/src/PIL/AniImagePlugin.py
@@ -0,0 +1,378 @@
+from io import BytesIO
+import struct
+from PIL import Image, CurImagePlugin, ImageFile, BmpImagePlugin
+from PIL._binary import i16le as i16
+from PIL._binary import i32le as i32
+from PIL._binary import o8
+from PIL._binary import o16le as o16
+from PIL._binary import o32le as o32
+
+def _accept(s):
+    return s[:4] == b'RIFF'
+
+
+def _save_frame(im: Image.Image, fp: BytesIO, filename: str, info: dict):
+    fp.write(b"\0\0\2\0")
+    bmp = True
+    sizes = info.get(
+        "sizes",
+        [(16, 16), (24, 24), (32, 32), (48, 48), (64, 64), (128, 128), (256, 256)],
+    )
+    hotspots = info.get("hotspots", [(0, 0) for i in range(len(sizes))])
+    if len(hotspots) != len(sizes):
+        raise ValueError("Number of hotspots must be equal to number of cursor sizes")
+
+    frames = []
+    width, height = im.size
+    for size in sorted(set(sizes)):
+        if size[0] > width or size[1] > height or size[0] > 256 or size[1] > 256:
+            continue
+
+        # TODO: invent a more convenient method for proportional scalings
+        frame = im.copy()
+        frame.thumbnail(size, Image.Resampling.LANCZOS, reducing_gap=None)
+        frames.append(frame)
+
+    fp.write(o16(len(frames)))  # idCount(2)
+    offset = fp.tell() + len(frames) * 16
+    for hotspot, frame in zip(hotspots, frames):
+        width, height = frame.size
+        # 0 means 256
+        fp.write(o8(width if width < 256 else 0))  # bWidth(1)
+        fp.write(o8(height if height < 256 else 0))  # bHeight(1)
+
+        bits, colors = BmpImagePlugin.SAVE[frame.mode][1:] if bmp else (32, 0)
+        fp.write(o8(colors))  # bColorCount(1)
+        fp.write(b"\0")  # bReserved(1)
+        fp.write(o16(hotspot[0]))  # x_hotspot(2)
+        fp.write(o16(hotspot[1]))  # y_hotspot(2)
+
+        image_io = BytesIO()
+        if bmp:
+            frame.save(image_io, "dib")
+
+            if bits != 32:
+                and_mask = Image.new("1", size)
+                ImageFile._save(
+                    and_mask, image_io, [("raw", (0, 0) + size, 0, ("1", 0, -1))]
+                )
+        else:
+            frame.save(image_io, "png")
+        image_io.seek(0)
+        image_bytes = image_io.read()
+        if bmp:
+            image_bytes = image_bytes[:8] + o32(height * 2) + image_bytes[12:]
+        bytes_len = len(image_bytes)
+        fp.write(o32(bytes_len))  # dwBytesInRes(4)
+        fp.write(o32(offset))  # dwImageOffset(4)
+        current = fp.tell()
+        fp.seek(offset)
+        fp.write(image_bytes)
+        offset = offset + bytes_len
+        fp.seek(current)
+
+def _write_single_frame(im: Image.Image, fp: BytesIO, filename: str):
+    fp.write(b"anih")
+    anih = o32(36) + o32(36) + (o32(1) * 2) + (o32(0) * 4) + o32(60) + o32(1)
+    fp.write(anih)
+    
+    fp.write(b"LIST" + o32(0))
+    list_offset = fp.tell()
+    fp.write(b"fram")
+
+    fp.write(b"icon" + o32(0))
+    icon_offset = fp.tell()
+    with BytesIO(b"") as icon_fp:
+        _save_frame(im, icon_fp, filename, im.encoderinfo)
+        icon_fp.seek(0)
+        icon_data = icon_fp.read()
+
+    fp.write(icon_data)
+    fram_end = fp.tell()
+    
+    fp.seek(icon_offset - 4)
+    icon_size = fram_end - icon_offset
+    fp.write(o32(icon_size))
+
+    fp.seek(list_offset - 4)
+    list_size = fram_end - list_offset
+    fp.write(o32(list_size))
+
+    fp.seek(fram_end)
+
+def _write_multiple_frames(im: Image.Image, fp: BytesIO, filename:str):  
+    anih_offset = fp.tell()
+    fp.write(b"anih" + o32(36))
+    fp.write(o32(0) * 9)
+
+    fp.write(b"LIST" + o32(0))
+    list_offset = fp.tell()
+    fp.write(b"fram")
+
+    frames = [im] + im.encoderinfo.get("append_images", [])
+    for frame in frames:
+        fp.write(b"icon" + o32(0))
+        icon_offset = fp.tell()
+        with BytesIO(b"") as icon_fp:
+            _save_frame(frame, icon_fp, filename, im.encoderinfo)
+            icon_fp.seek(0)
+            icon_data = icon_fp.read()
+
+        fp.write(icon_data)
+        fram_end = fp.tell()
+    
+        fp.seek(icon_offset - 4)
+        icon_size = fram_end - icon_offset
+        fp.write(o32(icon_size))
+
+        fp.seek(fram_end)
+
+    fp.seek(list_offset - 4)
+    list_size = fram_end - list_offset
+    fp.write(o32(list_size))
+
+    fp.seek(fram_end)
+
+    seq = im.encoderinfo.get("seq", [])
+    if seq:
+        fp.write(b"seq " + o32(0))
+        seq_offset = fp.tell()
+        for i in seq:
+            if i >= len(frames):
+                raise ValueError("Sequence index out of animation frame bounds")
+            
+            fp.write(o32(i))
+        
+        fram_end = fp.tell()
+        fp.seek(seq_offset - 4)
+        seq_size = fram_end - seq_offset
+        fp.write(o32(seq_size))
+
+        fp.seek(fram_end)
+
+    rate = im.encoderinfo.get("rate", [])
+    if rate:
+        fp.write(b"rate" + o32(0))
+        rate_offset = fp.tell()
+        
+        if seq:
+            if len(rate) != len(seq):
+                raise ValueError("Length of rate must match rate of sequence")
+        else:
+            if len(rate) != len(frames):
+                raise ValueError("Length of rate must match number of frames")
+        
+        for r in rate:
+            fp.write(o32(r))
+
+        fram_end = fp.tell()
+        fp.seek(rate_offset - 4)
+        rate_size = fram_end - rate_offset
+        fp.write(o32(rate_size))
+
+        fp.seek(fram_end)
+        
+    bmp = im.encoderinfo.get("bitmap_format") == "bmp"
+    display_rate = im.encoderinfo.get("display_rate", 2)
+    n_frames = len(frames)
+    n_steps = len(seq) if seq else n_frames
+    flag = 1 if not seq else 3
+
+    fram_end = fp.tell()
+
+    fp.seek(anih_offset)
+    fp.write(b"anih")
+    anih = o32(36) + o32(36) + o32(n_frames) + o32(n_steps) + (o32(0) * 4) + o32(display_rate) + o32(flag)
+    fp.write(anih)
+
+    fp.seek(fram_end)
+
+
+
+def _write_info(im: Image.Image, fp: BytesIO, filename: str):
+    fp.write(b"LIST" + o32(0))
+    list_offset = fp.tell()
+
+    inam = im.encoderinfo.get("inam", filename)
+    iart = im.encoderinfo.get("iart", "Pillow")
+
+    if isinstance(inam, str):
+        inam = inam.encode()
+    if not isinstance(inam, bytes):
+        raise TypeError("'inam' argument must be either a string or bytes")
+
+    if isinstance(iart, str):
+        iart = iart.encode()
+    if not isinstance(iart, bytes):
+        raise TypeError("'iart' argument must be either a string or bytes")
+
+    fp.write(b"INFO")
+    fp.write(b"INAM" + o32(0))
+    inam_offset = fp.tell()
+
+    fp.write(inam + b"\x00")
+    inam_size = fp.tell() - inam_offset
+
+    fp.write(b"IART" + o32(0))
+    iart_offset = fp.tell()    
+
+    fp.write(iart + b"\x00")
+    iart_size = fp.tell() - iart_offset
+
+    info_end = fp.tell()
+
+    fp.seek(iart_offset - 4)
+    fp.write(o32(iart_size))
+
+    fp.seek(inam_offset - 4)
+    fp.write(o32(inam_size))
+
+    fp.seek(list_offset - 4)
+    list_size = info_end - list_offset
+    fp.write(o32(list_size))
+    
+    fp.seek(info_end)
+
+def _save(im: Image.Image, fp: BytesIO, filename: str):
+    fp.write(b"RIFF\x00\x00\x00\x00")
+    riff_offset = fp.tell()
+
+    fp.write(b"ACON")
+    _write_info(im, fp, filename)
+    
+    frames = im.encoderinfo.get("append_images", [])
+    if frames:
+        _write_multiple_frames(im, fp, filename)
+    else:
+        _write_single_frame(im, fp, filename)
+    pass
+
+    riff_end = fp.tell()
+    fp.seek(riff_offset - 4)
+    riff_size = riff_end - riff_offset
+    fp.write(o32(riff_size))
+    
+    fp.seek(riff_end)
+
+class AniFile:
+    def __init__(self, buf: BytesIO) -> None:
+        self.image_data = []
+
+        self.buf = buf
+        self.rate = None
+        self.seq = None
+        self.anih = None
+
+        riff, size, fformat = struct.unpack('<4sI4s', buf.read(12))
+        if riff != b'RIFF':
+            SyntaxError("Not an ANI file")
+
+        self.riff = {
+            "size": size,
+            "fformat": fformat
+        }
+
+        chunkOffset = buf.tell()
+        while chunkOffset < self.riff['size']:
+            buf.seek(chunkOffset)
+            chunk, size = struct.unpack('<4sI', buf.read(8))
+            chunkOffset = chunkOffset + size + 8
+
+            if chunk == b'anih':
+                s = buf.read(36)
+                self.anih = {
+                    "size":  i32(s),  # Data structure size (in bytes)
+                    "nFrames": i32(s, 4),  # Number of frames
+                    "nSteps": i32(s, 8),  # Number of frames before repeat
+                    "iWidth": i32(s, 12),  # Width of frame (in pixels)
+                    "iHeight": i32(s, 16),  # Height of frame (in pixels)
+                    "iBitCount": i32(s, 20),  # Number of bits per pixel
+                    "nPlanes": i32(s, 24),  # Number of color planes
+                    # Default frame display rate (1/60th sec)
+                    "iDispRate": i32(s, 28),
+                    "bfAttributes": i32(s, 32),  # ANI attribute bit flags
+                }
+
+            if chunk == b'seq ':
+                s = buf.read(size)
+                self.seq = [i32(s, i*4) for i in range(size // 4)]
+
+            if chunk == b'rate':
+                s = buf.read(size)
+                self.rate = [i32(s, i*4) for i in range(size // 4)]
+
+            if chunk == b'LIST':
+                listtype = struct.unpack('<4s', buf.read(4))[0]
+                if listtype != b'fram':
+                    continue
+
+                listOffset = 0
+                while listOffset < size - 8:
+                    _, lSize = struct.unpack('<4sI', buf.read(8))
+                    self.image_data.append({"offset": buf.tell(), "size": lSize})
+
+                    buf.read(lSize)
+                    listOffset = listOffset + lSize + 8
+
+        if self.anih is None:
+            raise SyntaxError("not an ANI file")
+
+        if self.seq is None:
+            self.seq = [i for i in range(self.anih["nFrames"])]
+
+        if self.rate is None:
+            self.rate = [self.anih["iDispRate"] for i in range(self.anih["nFrames"])]
+
+    def frame(self, frame):
+        if frame > self.anih["nFrames"]:
+            raise ValueError("Frame index out of animation bounds")
+
+        offset, size = self.image_data[frame].values()
+        self.buf.seek(offset)
+        data = self.buf.read(size)
+
+        im = CurImagePlugin.CurImageFile(BytesIO(data))
+        return im
+        
+
+
+class AniImageFile(ImageFile.ImageFile):
+    format = "ANI"
+    format_description = "Windows Animated Cursor"
+    
+    def _open(self):       
+        self.ani = AniFile(self.fp)
+        self.frame = 0
+        self.seek(0)
+        self.size = self.im.size
+        self.info["seq"] = self.ani.seq
+        self.info["rate"] = self.ani.rate
+
+    @property
+    def size(self):
+        return self._size
+
+    @size.setter
+    def size(self, value):
+        if value not in self.info['sizes']:
+            raise ValueError("This is not one of the allowed sizes of this image")
+        self._size = value
+
+
+    def load(self):
+        im = self.ani.frame(self.frame)  
+        self.info['sizes'] = im.info['sizes']
+        self.im = im.im
+        self.mode = im.mode
+
+    def seek(self, frame):
+        if frame > self.ani.anih["nFrames"]:
+            raise ValueError("Frame index out of animation bounds")
+
+        self.frame = frame
+        self.load()
+
+        
+Image.register_open(AniImageFile.format, AniImageFile, _accept)
+Image.register_extension(AniImageFile.format, ".ani")
+Image.register_save(AniImageFile.format, _save)
\ No newline at end of file
diff --git a/src/PIL/__init__.py b/src/PIL/__init__.py
index e65b155b2..ab48f74e8 100644
--- a/src/PIL/__init__.py
+++ b/src/PIL/__init__.py
@@ -23,6 +23,7 @@ del _version
 
 
 _plugins = [
+    "AniImagePlugin",
     "BlpImagePlugin",
     "BmpImagePlugin",
     "BufrStubImagePlugin",