diff --git a/README.md b/README.md
index ceeb94cc..85fb87fa 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,119 @@ Based on manual test one-by-one:
 
 Feel free to open issue if anything is broken and I will take a look every several days. If I do not update this "Forge Status" then it means I cannot reproduce any problem. In that case, fresh re-install should help most.
 
+# UnetPatcher
+
+Below are self-supported **single file** of all codes to implement FreeU V2.
+
+See also `extension-builtin/sd_forge_freeu/scripts/forge_freeu.py`:
+
+```python
+import torch
+import gradio as gr
+
+from modules import scripts
+
+
+def Fourier_filter(x, threshold, scale):
+    # FFT
+    x_freq = torch.fft.fftn(x.float(), dim=(-2, -1))
+    x_freq = torch.fft.fftshift(x_freq, dim=(-2, -1))
+
+    B, C, H, W = x_freq.shape
+    mask = torch.ones((B, C, H, W), device=x.device)
+
+    crow, ccol = H // 2, W // 2
+    mask[..., crow - threshold:crow + threshold, ccol - threshold:ccol + threshold] = scale
+    x_freq = x_freq * mask
+
+    # IFFT
+    x_freq = torch.fft.ifftshift(x_freq, dim=(-2, -1))
+    x_filtered = torch.fft.ifftn(x_freq, dim=(-2, -1)).real
+
+    return x_filtered.to(x.dtype)
+
+
+def patch_freeu_v2(unet_patcher, b1, b2, s1, s2):
+    model_channels = unet_patcher.model.diffusion_model.config["model_channels"]
+    scale_dict = {model_channels * 4: (b1, s1), model_channels * 2: (b2, s2)}
+    on_cpu_devices = {}
+
+    def output_block_patch(h, hsp, transformer_options):
+        scale = scale_dict.get(h.shape[1], None)
+        if scale is not None:
+            hidden_mean = h.mean(1).unsqueeze(1)
+            B = hidden_mean.shape[0]
+            hidden_max, _ = torch.max(hidden_mean.view(B, -1), dim=-1, keepdim=True)
+            hidden_min, _ = torch.min(hidden_mean.view(B, -1), dim=-1, keepdim=True)
+            hidden_mean = (hidden_mean - hidden_min.unsqueeze(2).unsqueeze(3)) / (hidden_max - hidden_min).unsqueeze(2).unsqueeze(3)
+
+            h[:, :h.shape[1] // 2] = h[:, :h.shape[1] // 2] * ((scale[0] - 1) * hidden_mean + 1)
+
+            if hsp.device not in on_cpu_devices:
+                try:
+                    hsp = Fourier_filter(hsp, threshold=1, scale=scale[1])
+                except:
+                    print("Device", hsp.device, "does not support the torch.fft.")
+                    on_cpu_devices[hsp.device] = True
+                    hsp = Fourier_filter(hsp.cpu(), threshold=1, scale=scale[1]).to(hsp.device)
+            else:
+                hsp = Fourier_filter(hsp.cpu(), threshold=1, scale=scale[1]).to(hsp.device)
+
+        return h, hsp
+
+    m = unet_patcher.clone()
+    m.set_model_output_block_patch(output_block_patch)
+    return m
+
+
+class FreeUForForge(scripts.Script):
+    sorting_priority = 12  # It will be the 12th item on UI.
+
+    def title(self):
+        return "FreeU Integrated"
+
+    def show(self, is_img2img):
+        # make this extension visible in both txt2img and img2img tab.
+        return scripts.AlwaysVisible
+
+    def ui(self, *args, **kwargs):
+        with gr.Accordion(open=False, label=self.title()):
+            freeu_enabled = gr.Checkbox(label='Enabled', value=False)
+            freeu_b1 = gr.Slider(label='B1', minimum=0, maximum=2, step=0.01, value=1.01)
+            freeu_b2 = gr.Slider(label='B2', minimum=0, maximum=2, step=0.01, value=1.02)
+            freeu_s1 = gr.Slider(label='S1', minimum=0, maximum=4, step=0.01, value=0.99)
+            freeu_s2 = gr.Slider(label='S2', minimum=0, maximum=4, step=0.01, value=0.95)
+
+        return freeu_enabled, freeu_b1, freeu_b2, freeu_s1, freeu_s2
+
+    def process_before_every_sampling(self, p, *script_args, **kwargs):
+        # This will be called before every sampling.
+        # If you use highres fix, this will be called twice.
+
+        freeu_enabled, freeu_b1, freeu_b2, freeu_s1, freeu_s2 = script_args
+
+        if not freeu_enabled:
+            return
+
+        unet = p.sd_model.forge_objects.unet
+
+        unet = patch_freeu_v2(unet, freeu_b1, freeu_b2, freeu_s1, freeu_s2)
+
+        p.sd_model.forge_objects.unet = unet
+
+        # Below codes will add some logs to the texts below the image outputs on UI.
+        # The extra_generation_params does not influence results.
+        p.extra_generation_params.update(dict(
+            freeu_enabled=freeu_enabled,
+            freeu_b1=freeu_b1,
+            freeu_b2=freeu_b2,
+            freeu_s1=freeu_s1,
+            freeu_s2=freeu_s2,
+        ))
+
+        return
+```
+
 # Under Construction
 
 This Readme is under construction ... more docs/wiki coming soon ...